A257559 The slowest increasing sequence of semiprimes with strictly increasing difference of successive terms.

4, 6, 9, 14, 21, 33, 46, 62, 82, 106, 133, 161, 194, 235, 278, 323, 371, 422, 478, 535, 597, 662, 731, 802, 878, 955, 1037, 1121, 1207, 1294, 1382, 1473, 1565, 1658, 1754, 1851, 1954, 2059, 2165, 2279, 2395, 2513, 2638, 2771, 2906, 3043

Offset

1,1

Comments

Semiprime analog of A070865.

Heuristically a(n) is around n^2 log n/log log n. - Charles R Greathouse IV, May 01 2015

Links

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

Formula

a(n) >> n^2. - Charles R Greathouse IV, Apr 30 2015

Prog

(PARI) issemi(n)=bigomega(n)==2
t=0; print1(last=4); while(1, n=last+t; while(!issemi(n++), ); print1(", "n); t=n-last; last=n) \\ Charles R Greathouse IV, Apr 30 2015

Crossrefs

Cf. A001358, A070865.

Sequence in context: A339114 A175709 A073679 * A118689 A364489 A118692

Adjacent sequences: A257556 A257557 A257558 * A257560 A257561 A257562

Keyword

nonn

Author

Zak Seidov, Apr 30 2015

Status

approved