A252478 Products of a semiprime times a larger prime.

20, 28, 42, 44, 52, 66, 68, 76, 78, 92, 99, 102, 110, 114, 116, 117, 124, 130, 138, 148, 153, 164, 170, 171, 172, 174, 186, 188, 190, 207, 212, 222, 230, 236, 238, 244, 246, 255, 258, 261, 266, 268, 279, 282, 284, 285, 290, 292, 310, 316, 318, 322, 332, 333, 345, 354, 356, 366, 369, 370

Offset

1,1

Comments

Primitive elements of the sequence A137428 of numbers which have a composite divisor smaller than their largest prime factor: That sequence consists of all multiples of the terms of this sequence.

Links

Table of n, a(n) for n=1..60.

Formula

A252478 = { s*p ; s in A001358, p in A000040 and p > s }.

Prog

(PARI) is(n)={bittest(12, #f=factor(n)~) && f[1, #f]^2>n && setsearch([[2, 1], [1, 1, 1]], f[2, ])}

Crossrefs

Cf. A000040, A001358, A137428.

Sequence in context: A350841 A361867 A309769 * A124318 A309780 A139703

Adjacent sequences: A252475 A252476 A252477 * A252479 A252480 A252481

Keyword

nonn

Author

M. F. Hasler, Jan 02 2015

Status

approved