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 A072884 #19 Jun 03 2025 03:30:55 %S A072884 1,136,153,244,370,371,407,919,1459 %N A072884 3rd-order digital invariants: the sum of the cubes of the digits of n equals some number k and the sum of the cubes of the digits of k equals n. %D A072884 J.-M. De Koninck and A. Mercier, 1001 Problèmes en Théorie Classique Des Nombres, Problem 257 pp. 41; 185 Ellipses Paris 2004. %D A072884 David Wells, The Penguin Dictionary of Curious and Interesting Numbers, Revised Edition, London, England, 1997, pp. 124-125. %F A072884 k such that f(f(k)) = k, where f(k) = A055012(k). - _Lekraj Beedassy_, Sep 10 2004 %e A072884 136 is included because 1^3 + 3^3 + 6^3 = 244 and 2^3 + 4^3 + 4^3 = 136. %e A072884 244 is included because 2^3 + 4^3 + 4^3 = 136 and 1^3 + 3^6 + 6^3 = 244. %t A072884 f[n_] := Apply[Plus, IntegerDigits[Apply[Plus, IntegerDigits[n]^3]]^3]; Select[ Range[10^7], f[ # ] == # &] %t A072884 Select[Range[10000], Plus@@(IntegerDigits[Plus@@(IntegerDigits[ # ]^3)]^3)== #&] %Y A072884 Cf. A072409. %K A072884 nonn,fini,full,base %O A072884 1,2 %A A072884 _Robert G. Wilson v_ and _Harvey P. Dale_, Aug 09 2002