A175051 a(n) is the number of divisors of A175050(n).

1, 4, 4, 9, 9, 4, 8, 9, 16, 9, 9, 4, 9, 9, 9, 27, 16, 9, 9, 9, 25, 4, 9, 9, 27, 9, 8, 4, 27, 9, 16, 9, 9, 9, 16, 9, 9, 27, 9, 27, 4, 9, 9, 27, 27, 9, 9, 4, 9, 9, 9, 36, 9, 9, 9, 9, 16, 25, 27, 16, 27, 9, 27, 4, 9, 27, 27, 9, 9, 9, 9, 9, 9, 27, 16, 9, 9, 27, 9, 9, 9, 9, 9, 27, 9, 4, 9, 9, 9, 27, 64, 27

Offset: 1

Author

Leroy Quet, Dec 08 2009

Keywords

• nonn

Comments

All terms of this sequence (as well as all of those of sequence A175050) are perfect powers. (I.e., the terms of both of these sequences are terms of sequence A001597.)

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001597, A175050.

Programs

Mathematica

Block[{nn = 10^5, s}, s = Union@ Flatten@ Table[n^e, {e, Prime@ Range@ PrimePi@ Log2@ nn}, {n, nn^(1/e)}]; Select[DivisorSigma[0, s], MemberQ[s, #] &]] (* Michael De Vlieger, Nov 24 2017, after T. D. Noe at A001597 *)

Extensions

Extended by Ray Chandler, Dec 10 2009