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Revision History for A088604

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a(n) = smallest prime in which n substrings containing the least significant digit are primes.
(history; published version)

#10 by Joerg Arndt at Sat Sep 23 03:39:26 EDT 2023

STATUS

proposed

approved

#9 by Michel Marcus at Sat Sep 23 03:22:47 EDT 2023

STATUS

editing

proposed

#8 by Michel Marcus at Sat Sep 23 03:22:37 EDT 2023

PROG

(PARI) f(n, d, digs, spare) = local(p, r, found); if (!d, return(n)); found = 0; for (i = 0, 9, p = n + i*10^digs; if ((i && isprime(p)) || spare, r = f(p, d - 1, digs + 1, spare - 1 + (i && isprime(p)))); if (r && (r < found || !found), found = r)); found; a(n) = local(i, r); i = 0; while (1, r = f(0, n + i, 0, i); if (r, return(r), i++)); (Wasserman)

a(n) = local(i, r); i = 0; while (1, r = f(0, n + i, 0, i); if (r, return(r), i++)); \\ David Wasserman, Aug 12 2005

STATUS

approved

editing

#7 by N. J. A. Sloane at Thu Dec 05 19:56:34 EST 2013

AUTHOR

_Amarnath Murthy (amarnath_murthy(AT)yahoo.com), _, Oct 15 2003

Discussion

Thu Dec 05

19:56

OEIS Server: https://oeis.org/edit/global/2075

#6 by Russ Cox at Sat Mar 31 13:20:51 EDT 2012

COMMENTS

We exclude substrings that begin with 0, so a(3) is not 103. - _David Wasserman (wasserma(AT)spawar.navy.mil), _, Aug 12 2005

EXTENSIONS

More terms from _David Wasserman (wasserma(AT)spawar.navy.mil), _, Aug 12 2005

Discussion

Sat Mar 31

13:20

OEIS Server: https://oeis.org/edit/global/880

#5 by Russ Cox at Fri Mar 30 17:29:12 EDT 2012

COMMENTS

Agrees with A127891 for 24 terms, but A127891 ends there while this sequence continues. - _Ray Chandler (rayjchandler(AT)sbcglobal.net), _, Mar 13 2007

Discussion

Fri Mar 30

17:29

OEIS Server: https://oeis.org/edit/global/154

#4 by N. J. A. Sloane at Fri May 11 03:00:00 EDT 2007

COMMENTS

Agrees with A127891 for 24 terms, but A127891 ends there while this sequence continues. - Ray Chandler (rayjchandler(AT)sbcglobal.net), Mar 13 2007

EXAMPLE

a(4) = 2113 1223 in which the four substrings containing the LSD (3,13,113,211323,223,1223) are primes.

CROSSREFS

Cf. A088603, A127891.

KEYWORD

base,nonn,new

#3 by N. J. A. Sloane at Wed Dec 06 03:00:00 EST 2006

NAME

a(n) = smallest prime in which n substrings containing the least significant digit are primeprimes.

EXAMPLE

a(4) = 2113 in which the four substrings containing the LSD (3,13,113,2113) are primeprimes.

KEYWORD

base,nonn,new

#2 by N. J. A. Sloane at Wed Sep 21 03:00:00 EDT 2005

DATA

2, 13, 113, 2113, 1223, 12113, 612113121283, 1237547, 12184967, 124536947, 1219861613, 12181833347, 121339693967, 1213536676883, 12673876537547, 121848768729173, 1275463876537547, 12429121339693967, 165678739293946997

COMMENTS

We exclude substrings that begin with 0, so a(3) is not 103. - David Wasserman (wasserma(AT)spawar.navy.mil), Aug 12 2005

PROG

KEYWORD

base,hard,more,nonn,new

base,nonn

EXTENSIONS

More terms from David Wasserman (wasserma(AT)spawar.navy.mil), Aug 12 2005

#1 by N. J. A. Sloane at Thu Feb 19 03:00:00 EST 2004

NAME

a(n) = smallest prime in which n substrings containing the least significant digit are prime.

DATA

2, 13, 113, 2113, 12113, 612113

OFFSET

1,1

COMMENTS

a(n) need not contain a(n-1) as a substring.

EXAMPLE

a(4) = 2113 in which the four substrings containing the LSD (3,13,113,2113) are prime.

CROSSREFS

Cf. A088603.

KEYWORD

base,hard,more,nonn

AUTHOR

Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 15 2003

STATUS

approved