A187711 - OEIS

A187711

Integers k which equal (product of divisors of k) mod (sum of divisors of k).

2, 3, 5, 7, 10, 11, 13, 17, 19, 20, 23, 29, 31, 33, 37, 40, 41, 43, 47, 53, 59, 61, 67, 71, 73, 76, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 136, 137, 139, 145, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 207, 211, 223, 227, 229, 233, 239, 241, 251, 257, 261, 263, 269, 271, 277

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..10000

FORMULA

{ k : k = A187680(k) }.

MAPLE

isA187711 := proc(n) is(A187680(n) = n) end proc:

for n from 2 to 300 do if isA187711(n) then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Mar 17 2011

MATHEMATICA

Select[Range[300], Mod[#^(DivisorSigma[0, #]/2), DivisorSigma[1, #]] == # &] (* G. C. Greubel, Nov 05 2018 *)