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%I #7 Oct 29 2012 13:36:31
%S 55,136,160,919
%N Recurring digital invariants of order 3.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/RecurringDigitalInvariant.html">Recurring Digital Invariant</a>
%e 136: 1^3 + 3^3 + 6^3 = 244
%e 244: 2^3 + 4^3 + 4^3 = 136,
%e so 136 is an order 3 recurring digital invariant.
%t lst = {}; f[n_] := Total[IntegerDigits[n]^3]; Do[a = n; Do[a = f[a]; If[a < n, Break[]]; If[a == n && ! n == f[n], AppendTo[lst, n]; Break[]], {3}], {n, 10^3}]; lst
%Y Cf. A218246-A218248.
%K base,fini,full,nonn
%O 1,1
%A _Arkadiusz Wesolowski_, Oct 22 2012
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