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 A045503 #20 Oct 01 2024 13:16:56
%S A045503 1,1,4,27,256,3125,46656,823543,16777216,387420489,2,2,5,28,257,3126,
%T A045503 46657,823544,16777217,387420490,5,5,8,31,260,3129,46660,823547,
%U A045503 16777220,387420493,28,28,31,54,283,3152,46683,823570,16777243,387420516,257,257,260
%N A045503 If decimal expansion of n is ab...d, a(n) = a^a + b^b +...+ d^d.
%H A045503 Harvey P. Dale, <a href="/A045503/b045503.txt">Table of n, a(n) for n = 0..1000</a>
%p A045503 a:= n-> add(i^i, i=convert(n,base,10)):
%p A045503 seq(a(n), n=0..42); # _Alois P. Heinz_, Apr 29 2022
%t A045503 f[n_]:=Module[{idn=IntegerDigits[n]/.{0->1}},Total[idn^idn]]; Array[f,100,0] (* _Harvey P. Dale_, May 14 2012 *)
%o A045503 (PARI) a(n)=if(n, n=digits(n); sum(i=1,#n,n[i]^n[i]), 1) \\ _Charles R Greathouse IV_, Oct 07 2015
%o A045503 (PARI) apply( {A045503(n)=vecsum([d^d|d<-digits(n+!n)])}, [0..44]) \\ _M. F. Hasler_, Oct 01 2024
%Y A045503 Cf. A045512 (excludes zero digits).
%K A045503 nonn,base
%O A045503 0,3
%A A045503 _Jeff Burch_
%E A045503 Checked by Neven Juric (neven.juric(AT)apis-it.hr), Feb 04 2008