A281824 Numbers that are the sum of 6 consecutive semiprimes.

58, 75, 91, 107, 123, 142, 161, 175, 191, 205, 225, 241, 258, 278, 297, 316, 332, 348, 366, 385, 405, 429, 452, 473, 491, 508, 524, 536, 546, 566, 590, 614, 639, 664, 690, 706, 718, 732, 747, 762, 782, 802, 822, 838, 851, 872, 889, 906, 924, 945, 968, 990

Offset: 1

Author

Zak Seidov, Jan 31 2017

Keywords

• nonn

Comments

Semiprime analog of A127333. First terms that are also in A127333: 690, 990, 1172, 1250, 1286, 2288, 4798, 5064.

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001358, A127333.

Programs

Mathematica

Total /@ Partition[Select[Range[4, 200], 2 == PrimeOmega[#] &], 6, 1]

PARI

do(n)=my(v=List([58]),u=List(),t=58); forprime(p=2,n\2, forprime(q=2,min(p,n\p), listput(u,p*q))); u=Set(u); for(i=7,#u, listput(v, t+=u[i]-u[i-6])); Set(v) \\ Charles R Greathouse IV, Jan 31 2017

Formula

a(n) ~ 6n log n/log log n. - Charles R Greathouse IV, Jan 31 2017