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

Offset: 1

Author

Juri-Stepan Gerasimov, Mar 17 2011

Keywords

• nonn

Links

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

Crossrefs

Cf. A000203, A007955, A187680.

Programs

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 *)

Formula

{ k : k = A187680(k) }.