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 A066588 #30 Dec 04 2024 17:51:10
%S A066588 1,1,4,9,13,11,27,25,37,45,1,41,54,58,52,99,88,98,108,127,31,117,148,
%T A066588 146,153,151,154,189,163,167,63,184,205,207,214,260,270,271,265,306,
%U A066588 112,308,315,313,325,306,352,374,333,355,151,414,412,350,378,442,391,450
%N A066588 a(n) = sum of the digits of n^n.
%H A066588 Harry J. Smith, <a href="/A066588/b066588.txt">Table of n, a(n) for n = 0..1000</a>
%e A066588 a(7) = 25 because 7^7 = 823543 and 8 + 2 + 3 + 5 + 4 + 3 = 25.
%p A066588 a:= n-> add(i, i=convert(n^n, base, 10)):
%p A066588 seq(a(n), n=0..60); # _Alois P. Heinz_, Oct 06 2023
%t A066588 Table[Plus@@IntegerDigits@(n^n), {n, 80}] (* _Vincenzo Librandi_, Jun 18 2015 *)
%o A066588 (PARI) a(n) = sumdigits(n^n) \\ _Michel Marcus_, Jun 18 2015
%o A066588 (Magma) [&+Intseq((n^n)): n in [0..80] ]; // _Vincenzo Librandi_, Jun 18 2015
%Y A066588 Cf. A000312, A007953, A004152.
%K A066588 base,nonn
%O A066588 0,3
%A A066588 Robert A. Stump (bee_ess107(AT)yahoo.com), Jan 07 2002
%E A066588 More terms from _Paolo P. Lava_, May 15 2007
%E A066588 a(0)=1 inserted by _Sean A. Irvine_, Oct 06 2023