A109727 Number of admirable numbers < 10^n.

0, 13, 65, 379, 2549, 19480, 159001, 1345929, 11676912, 103136395

Offset: 1

Author

Jason Earls, Aug 10 2005

Keywords

• nonn

Crossrefs

Cf. A111592.

Programs

Mathematica

fQ[n_] := Block[{d = Most[Divisors[n]], k = 1}, l = Length[d]; s = Plus @@ d; While[k < l && s - 2d[[k]] > n, k++ ]; If[k > l || s != n + 2d[[k]], False, True]]; c = 0; k = 1; Do[ While[k <= 10^n, If[ fQ[k], c++ ]; k++ ]; k++; Print[c], {n, 7}] (* Robert G. Wilson v *)

Extensions

a(7) from Robert G. Wilson v, Aug 13 2005

a(8)-a(10) from Donovan Johnson, Jan 25 2012