A175115 An integer k, k >=3, is included if d(k) = d(k-1)*d(k-2), where d(k) is the number of divisors of k.

3, 24, 120, 150, 195, 216, 294, 312, 399, 440, 459, 525, 540, 558, 570, 615, 630, 663, 693, 696, 744, 759, 774, 858, 999, 1032, 1095, 1125, 1152, 1176, 1239, 1350, 1455, 1470, 1494, 1608, 1624, 1659, 1664, 1710, 1725, 1734, 1785, 1860, 1880, 1896, 1914

Offset

1,1

Comments

Terms calculated by M. F. Hasler.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Mathematica

Transpose[Select[Partition[Range[2000], 3, 1], DivisorSigma[0, Last[#]] == DivisorSigma[0, First[#]] * DivisorSigma[0, #[[2]]]&]][[1]] + 2 (* Amiram Eldar, Jul 17 2019 after Harvey P. Dale at A175116 *)

Crossrefs

Cf. A000005, A175116, A145469.

Sequence in context: A139031 A065692 A127520 * A301812 A268633 A324065

Adjacent sequences: A175112 A175113 A175114 * A175116 A175117 A175118

Keyword

nonn

Author

Leroy Quet, Feb 13 2010

Status

approved