The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A330508 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A330508

Numbers k such that k + 6^t is semiprime for t = 0 to 9.
(history; published version)

#18 by Charles R Greathouse IV at Thu Sep 08 08:46:24 EDT 2022

PROG

(MAGMAMagma) f:=func<n|&+[d[2]: d in Factorization(n)] eq 2>; [k:k in [1..2100000]|forall{m:m in [0..9]|f(k+6^m)}]; // Marius A. Burtea, Dec 20 2019

Discussion

Thu Sep 08

08:46

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

#17 by Charles R Greathouse IV at Fri Dec 20 02:15:30 EST 2019

STATUS

editing

approved

#16 by Charles R Greathouse IV at Fri Dec 20 02:15:25 EST 2019

LINKS

Charles R Greathouse IV, <a href="/A330508/b330508.txt">Table of n, a(n) for n = 1..10000</a>

STATUS

approved

editing

#15 by Charles R Greathouse IV at Fri Dec 20 02:14:54 EST 2019

STATUS

proposed

approved

#14 by Charles R Greathouse IV at Fri Dec 20 02:10:20 EST 2019

STATUS

editing

proposed

#13 by Charles R Greathouse IV at Fri Dec 20 02:10:11 EST 2019

COMMENTS

a(2620) = 530079693 is the first multiple of 3 in this sequence; there are no multiples of 2. - Charles R Greathouse IV, Dec 20 2019

#12 by Charles R Greathouse IV at Fri Dec 20 02:06:25 EST 2019

CROSSREFS

Subsequence of A076274.

#11 by Charles R Greathouse IV at Fri Dec 20 02:03:52 EST 2019

PROG

v=Listis(n); forprime=for(pt=2, 1e6, 0, 9, if(is!issemi(2*p-1n+6^t), listputreturn(v, 2*p-0))); 1))); Vec(v) \\ Charles R Greathouse IV, Dec 20 2019

CROSSREFS

Subsequence of A076274.

#10 by Charles R Greathouse IV at Fri Dec 20 01:58:10 EST 2019

PROG

(PARI) issemi(n)=bigomega(n)==2

v=List(); forprime(p=2, 1e6, if(is(2*p-1), listput(v, 2*p-1))); Vec(v) \\ Charles R Greathouse IV, Dec 20 2019

CROSSREFS

Subsequence of A076274.

STATUS

proposed

editing

#9 by Marius A. Burtea at Fri Dec 20 01:40:52 EST 2019

STATUS

editing

proposed