A031125 Number of proper factorizations of p1^n*p2^2, where p1 and p2 are distinct primes.

1, 3, 8, 15, 28, 46, 76, 117, 180, 266, 391, 559, 796, 1110, 1540, 2105, 2862, 3845, 5141, 6807, 8972, 11732, 15274, 19752, 25442, 32581, 41568, 52769, 66756, 84077, 105554, 131994, 164565, 204449, 253291, 312798, 385284, 473182, 579721, 708352

Offset

0,2

Links

Ray Chandler, Table of n, a(n) for n = 0..10000

Formula

a(n) = A000291(n) - 1 = A028422(2^n*3^2). - Ray Chandler, May 01 2017

Crossrefs

Cf. A000291, A028422.

Sequence in context: A047873 A036419 A054107 * A294423 A294426 A097589

Adjacent sequences: A031122 A031123 A031124 * A031126 A031127 A031128

Keyword

nonn

Author

Jeff Burch

Extensions

Offset changed to 0 and more terms added by Ray Chandler, May 01 2017

Status

approved