A175051 - OEIS

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

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OFFSET

1,2

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

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 *)

CROSSREFS

Cf. A001597, A175050.

Sequence in context: A362294 A198497 A231980 * A011364 A016713 A343620

Adjacent sequences: A175048 A175049 A175050 * A175052 A175053 A175054

KEYWORD

nonn

AUTHOR

Leroy Quet, Dec 08 2009

EXTENSIONS

Extended by Ray Chandler, Dec 10 2009

STATUS

approved