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Revision History for A113008

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Showing entries 1-10 | older changes

A113008

Numbers n such that n, n+1, n+2, n+3 and n+4 are respectively 1,2,3,4,5-almost primes.
(history; published version)

#18 by Harvey P. Dale at Sat Dec 17 15:59:55 EST 2022

STATUS

editing

approved

#17 by Harvey P. Dale at Sat Dec 17 15:59:52 EST 2022

MATHEMATICA

aprQ[p_]:=Total[FactorInteger[#][[All, 2]]]&/@Range[p+1, p+4]=={2, 3, 4, 5}; Select[ Prime[ Range[120000]], aprQ] (* Harvey P. Dale, Dec 17 2022 *)

STATUS

approved

editing

#16 by Charles R Greathouse IV at Thu Sep 08 08:45:23 EDT 2022

PROG

(MAGMAMagma) [n: n in PrimesUpTo(2*10^6) | forall{k: k in [1..4] | &+[f[j, 2]: j in [1..#f]] eq k+1 where f is Factorization(n+k)}]; // Vincenzo Librandi, Sep 24 2012

Discussion

Thu Sep 08

08:45

OEIS Server: https://oeis.org/edit/global/2944

#15 by OEIS Server at Sun Feb 05 15:04:54 EST 2017

LINKS

Charles R Greathouse IV, <a href="/A113008/b113008_1.txt">Table of n, a(n) for n = 1..10000</a>

#14 by Charles R Greathouse IV at Sun Feb 05 15:04:54 EST 2017

STATUS

editing

approved

Discussion

Sun Feb 05

15:04

OEIS Server: Installed new b-file as b113008.txt.  Old b-file is now b113008_1.txt.

#13 by Charles R Greathouse IV at Sun Feb 05 14:47:39 EST 2017

LINKS

Vincenzo Librandi, Charles R Greathouse IV, <a href="/A113008/b113008_1.txt">Table of n, a(n) for n = 1..100010000</a>

PROG

(PARI) list(lim)=my(v=List(), L=(lim+2)\3, t); forprime(p=3, L\3, forprime(q=3, min(L\p, p), t=3*p*q-2; if(t%12==1 && isprime(t) && isprime((t+1)/2) && bigomega(t+3)==4 && bigomega(t+4)==5, listput(v, t)))); Set(v) \\ Charles R Greathouse IV, Feb 05 2017

STATUS

approved

editing

#12 by N. J. A. Sloane at Thu Oct 31 12:17:34 EDT 2013

MATHEMATICA

f[n_] := Plus @@ Last /@ FactorInteger@n; t = {}; Do[p = Prime[n]; If[Array[ f[p + # ] &, 4] == {2, 3, 4, 5}, AppendTo[t, p]], {n, 126483}]; t (* _Robert G. Wilson v _ *)

Discussion

Thu Oct 31

12:17

OEIS Server: https://oeis.org/edit/global/2036

#11 by Bruno Berselli at Mon Sep 24 05:11:50 EDT 2012

STATUS

editing

approved

#10 by Bruno Berselli at Mon Sep 24 05:11:06 EDT 2012

PROG

(MAGMA) [n: n in PrimesUpTo(2*10^6) | forall{k: k in [1..4] | &+[f[j, 2]: j in [1..#f]] eq k +1 where f is Factorization(n +k)}]; // Vincenzo Librandi, Sep 24 2012

STATUS

proposed

editing

#9 by Vincenzo Librandi at Mon Sep 24 03:24:56 EDT 2012

STATUS

editing

proposed