A344731 Numbers k such that k divides A306069(k).

1, 275, 277, 3337, 3353, 3359, 39675, 39689, 472467, 797806459, 9501109507

Offset: 1

Author

Amiram Eldar, May 27 2021

Keywords

• nonn
• more

Comments

The corresponding quotients A306069(k)/k are 1, 5, 5, 7, 7, 7, 9, 9, 11, 17, 19, ...

a(12) > 7.5*10^10, if it exists.

Examples

			a(1) = 1 since A306069(1) = 1 is divisible by 1.
a(2) = 275 since A306069(275) = 1375 = 5 * 275 is divisible by 275.
		

Crossrefs

Cf. A286324, A306069.

The bi-unitary version of A050226.

Similar sequences: A064610, A344732, A344733.

Programs

Mathematica

f[p_, e_] := If[Mod[e, 2] == 1, (e + 1), e]; s[1] = 1; s[n_] := s[n] = s[n - 1] + Times @@ f @@@ FactorInteger[n]; Select[Range[40000], Divisible[s[#], #] &]