OFFSET
1,2
LINKS
Donovan Johnson and Giovanni Resta, Table of n, a(n) for n = 1..1096 (terms < 10^11, first 500 terms from Donovan Johnson)
EXAMPLE
n = 5000 = 2*2*2*5*5*5*5, tau(5000) = 20 = 2*2*5, common prime factors: {2,5}
MATHEMATICA
ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] Do[s=ba[DivisorSigma[0, n]]; If[Equal[s, ba[n]], Print[n]], {n, 1, 10000}]
PROG
(PARI) is(n)=my(f=factor(n)); factor(numdiv(f))[, 1]==f[, 1] \\ Charles R Greathouse IV, Oct 19 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Mar 26 2003
STATUS
approved