This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A130680 #9 Oct 18 2013 10:28:51
%S A130680 1,1215,3700,11680,13608,87949
%N A130680 Numbers n such that n = (a_1 + a_2 + ... + a_p)*(a_1^3 + a_2^3 + ... + a_p^3), where n has the decimal expansion a_1a_2...a_p.
%C A130680 This sequence is finite and all the terms are listed. Proof: Let a_1a_2...a_p be the decimal expansion of n. Then p <= log_10(n)+1. Furthermore we have a_i <= 9, therefore (a_1 + a_2 + ... + a_p) <= 9*(log_10(n)+1) and (a_1^3 + a_2^3 + ... + a_p^3) <= 9^3*(log_10(n)+1). On the other hand, for all n > 300000 we have 9^4*(log_10(n)+1)^2 < n. A computer search confirms that we indeed have found all terms.
%e A130680 87949 = (8+7+9+4+9)*(8^3+7^3+9^3+4^3+9^3).
%t A130680 For[n = 1, n < 1000000, n++, b = IntegerDigits[n]; If[Sum[b[[i]], {i, 1, Length[b]}] * Sum[b[[i]]^3, {i, 1, Length[b]}] == n, Print[n]]]
%t A130680 ffQ[n_]:=Module[{c=IntegerDigits[n]},Total[c]Total[c^3]==n]; Select[ Range[ 90000],ffQ] (* _Harvey P. Dale_, Oct 18 2013 *)
%Y A130680 Cf. A115518.
%K A130680 base,fini,full,nonn
%O A130680 1,2
%A A130680 _Yalcin Aktar_, Jun 29 2007
%E A130680 Edited by _Stefan Steinerberger_, Jul 13 2007