A174900 a(n) = the smallest numbers k such that A007955(k) = n, or 0 if there is no such k, where A007955(m) = product of divisors of m.

1, 2, 3, 0, 5, 0, 7, 4, 0, 0, 11, 0, 13, 0, 0, 0, 17, 0, 19, 0, 0, 0, 23, 0, 0, 0, 9, 0, 29, 0, 31, 0, 0, 0, 0, 6, 37, 0, 0, 0, 41, 0, 43, 0, 0, 0, 47, 0, 0, 0, 0, 0, 53, 0, 0, 0, 0, 0, 59, 0, 61, 0, 0, 8, 0, 0, 67, 0, 0, 0, 71, 0, 73, 0, 0, 0, 0, 0, 79, 0, 0, 0, 83

Offset

1,2

Comments

a(n) = the largest numbers k such that A007955 (k) = n, or 0 if there is no such k.

Links

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

Mathematica

With[{m = 100}, s[n_] := n^(DivisorSigma[0, n]/2); (FirstPosition[Array[s, m], #] & /@ Range[m]) /. Missing["NotFound"] -> 0 // Flatten] (* Amiram Eldar, Aug 06 2024 *)

Crossrefs

Cf. A007955.

Sequence in context: A365276 A101991 A296065 * A344369 A175880 A071376

Adjacent sequences: A174897 A174898 A174899 * A174901 A174902 A174903

Keyword

nonn

Author

Jaroslav Krizek, Apr 01 2010

Extensions

More terms from Amiram Eldar, Aug 06 2024

Status

approved