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Revision History for A243886

(Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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Primes p = prime(n): such that p.n and n.p both are prime, where (.) indicates concatenation.
(history; published version)

#10 by Michel Marcus at Sun Jun 15 08:48:55 EDT 2014

STATUS

reviewed

approved

#9 by Franklin T. Adams-Watters at Sun Jun 15 02:23:47 EDT 2014

STATUS

proposed

reviewed

#8 by K. D. Bajpai at Sun Jun 15 01:30:48 EDT 2014

STATUS

editing

proposed

#7 by K. D. Bajpai at Sun Jun 15 01:30:41 EDT 2014

EXAMPLE

1051 is in the sequence because 661 1051 = prime(177): Concatenation of [1051.177 = 1051177] and concatenation of [177.1051 = 1771051] which are also primes.

STATUS

proposed

editing

#6 by Wesley Ivan Hurt at Sat Jun 14 13:09:24 EDT 2014

STATUS

editing

proposed

Discussion

Sat Jun 14

13:31

Alonso del Arte: No one had submitted this before? Huh, interesting.

#5 by Wesley Ivan Hurt at Sat Jun 14 13:09:13 EDT 2014

COMMENTS

Intersection of A084671 and A166283.

STATUS

proposed

editing

#4 by K. D. Bajpai at Fri Jun 13 12:54:32 EDT 2014

STATUS

editing

proposed

#3 by K. D. Bajpai at Fri Jun 13 12:53:08 EDT 2014

COMMENTS

Intersection of A084671 and A166283.

LINKS

K. D. Bajpai, <a href="/A243886/b243886.txt">Table of n, a(n) for n = 1..10000</a>

MAPLE

with(numtheory): with(StringTools): A243886:= proc() local p, k1, k2; p:=ithprime(n); k1:=parse (cat (p, n)); k2:=parse(cat(n, p)); if isprime(k1)and isprime(k2) then RETURN (p); fi; end: seq(A243886 (), n=1..5000);

#2 by K. D. Bajpai at Fri Jun 13 12:49:45 EDT 2014

NAME

allocated for K. D. Bajpai

Primes p = prime(n): such that p.n and n.p both are prime, where (.) indicates concatenation.

DATA

661, 1051, 1999, 2179, 3433, 3593, 3719, 4073, 4591, 4733, 5449, 5503, 6079, 6481, 7109, 7211, 7489, 8293, 8513, 9901, 10273, 10529, 11821, 12721, 14107, 14591, 14879, 15263, 15877, 18149, 19559, 22027, 22129, 22571, 23339, 24527, 25357, 26881, 27337, 34259

OFFSET

1,1

EXAMPLE

661 is in the sequence because 661 = prime(121): Concatenations of [661.121 = 661121] and concatenation of [121.661 = 121661] which are also primes.

1051 is in the sequence because 661 = prime(177): Concatenation of [1051.177 = 1051177] and concatenation of [177.1051 = 1771051] which are also primes.

MATHEMATICA

Select[Prime [Range[5000]], PrimeQ[FromDigits[Join[IntegerDigits [PrimePi [#]], IntegerDigits [#]]]] && PrimeQ [FromDigits [Join [IntegerDigits[#], IntegerDigits [PrimePi [#]]]]] &]

CROSSREFS

Cf. A000040, A084671, A166283.

KEYWORD

allocated

nonn,base,new

AUTHOR

K. D. Bajpai, Jun 13 2014

STATUS

approved

editing

#1 by K. D. Bajpai at Fri Jun 13 12:49:45 EDT 2014

NAME

allocated for K. D. Bajpai

KEYWORD

allocated

STATUS

approved