OFFSET
1,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
MATHEMATICA
With[{nn=300}, Select[Thread[{FoldList[Times, DivisorSigma[0, Range[ nn]]], Range[ nn]}], IntegerQ[#[[1]]/#[[2]]]&]][[All, 2]] (* Harvey P. Dale, Mar 05 2019 *)
PROG
(Magma) [ n: n in [1..260] | &*[ NumberOfDivisors(k): k in [1..n] ] mod n eq 0 ]; // Klaus Brockhaus, Nov 05 2008
(PARI) isok(k) = frac(prod(i=1, k, numdiv(i))/k) == 0; \\ Michel Marcus, Feb 06 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Ctibor O. Zizka, Nov 04 2008
EXTENSIONS
Extended beyond a(12) by Klaus Brockhaus, Nov 05 2008
STATUS
approved