A217357 Semiprimes p such that next semiprime after p is p+30.

32777, 88649, 91799, 113107, 165697, 273257, 310103, 322211, 326137, 460963, 466063, 468877, 480443, 483223, 506509, 509131, 553349, 564347, 565493, 587611, 616771, 623257, 624959, 625619, 739177, 766799, 777163, 826657, 832357, 834123, 845177, 860873, 916163

Offset

1,1

Comments

Smallest difference between two consecutive terms occurs first at a(329) = 5861197 because a(330) = 5861227 and 5861227 - 5861197 = 30. Same difference for a(1212) = 16179703, a(1630) = 20611897 and a(1641) = 20703923.- Zak Seidov, Feb 14 2017

Links

Zak Seidov, Table of n, a(n) for n = 1..1000

Example

32777 =A001358(8112)  = 73*449, 32807 = A001358(8113) = 3*619,
88649 =A001358(20880)  = 11*8059, 88679 = A001358(20881) = 71*1249.

Mathematica

Select[Partition[Select[Range[10^6], PrimeOmega[#]==2&], 2, 1], #[[2]]-#[[1]] == 30&][[All, 1]] (* Harvey P. Dale, May 06 2022 *)

Prog

(Magma) IsSemiprime:=func<n | &+[d[2]: d in Factorization(n)] eq 2>; [n: n in [4..1000000] | IsSemiprime(n) and IsSemiprime(n+30) and forall{n+i: i in [1..29] | not IsSemiprime(n+i)}]; // Bruno Berselli, Oct 01 2012

Crossrefs

Cf. A001358, A065516, A217030, A217335.

Sequence in context: A017693 A013963 A036093 * A083603 A168634 A045061

Adjacent sequences: A217354 A217355 A217356 * A217358 A217359 A217360

Keyword

nonn

Author

Zak Seidov, Oct 01 2012

Status

approved