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 A219111 #8 Mar 14 2015 10:11:58 %S A219111 1,10,100,1000,10000,11123,11132,11213,11231,11312,11321,12113,12131, %T A219111 12311,13112,13121,13211,21113,21131,21311,23111,31112,31121,31211, %U A219111 32111,44688,44868,44886,46488,46848,46884,48468,48486,48648,48684,48846,48864,64488 %N A219111 Numbers that eventually reach 1 under "x -> sum of 4th power of digits of x". %e A219111 11123 is in the sequence because 1^4 +1^4+1^4+2^4+3^4 = 100 and 1^4 + 0^4 + 0^4 = 1. %e A219111 2 is not in the sequence because 2 --> 16 --> 1297 -->8979 -->19619 -->14420 -->529 -->7202 -->2433 -->434 -->593 -->7267 -->6114 -->1554 -->1507 -->3027 -->2498 -->10929 -->13139 -->6725 -->4338 -->4514 -->1138 -->4179 -->9219 -->13139 which repeats with period 7, so never reaches 1. %t A219111 Select[Range[50000], FixedPoint[Total[IntegerDigits[#]^4]&, #, 10]==1&] %Y A219111 Cf. A007770, A035504. %K A219111 nonn,base %O A219111 1,2 %A A219111 _Michel Lagneau_, Nov 12 2012