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 A076015 #27 May 31 2024 22:11:05
%S A076015 1,3,14,100,979,12201,184820,3297456,67731333,1574304985,40851766526,
%T A076015 1170684360924,36720042483591,1251308658130545,46034015337733480,
%U A076015 1818399978159990976,76762718946972480009
%N A076015 Sum of the (n-1)-th powers of the first n integers.
%C A076015 a(n) is the number of length n sequences of [n] that start with their maximum value.
%C A076015 By symmetry, counts many other simple classes of endofunctions.
%H A076015 Seiichi Manyama, <a href="/A076015/b076015.txt">Table of n, a(n) for n = 1..387</a>
%F A076015 a(n) = Sum_{m=1..n} m^(n-1), n >= 1.
%e A076015 The 3 sequences for n=2 are 11, 21, 22.
%e A076015 The 14 = 3^0 + 3^1 + 3^2 sequences starting with their maximum value for n=3 are 111, 211, 212, 221, 222, 311, 312, 313, 321, 322, 323, 331, 332, 333.
%p A076015 a:=n->sum((n-j+1)^n,j=0..n): seq(a(n), n=0..17); # _Zerinvary Lajos_, Jun 05 2008
%t A076015 f[n_]:=Module[{s=0},Do[s+=a^n,{a,0,n+1}]; s]; Table[f[n],{n,20}] (* _Vladimir Joseph Stephan Orlovsky_, Feb 18 2010 *)
%t A076015 Table[Sum[m^(n-1),{m,n}],{n,20}] (* _Harvey P. Dale_, Jan 26 2016 *)
%o A076015 (PARI) vector(20, n, sum(m=1, n, m^(n-1))) \\ _Michel Marcus_, Jan 14 2015
%Y A076015 Cf. A076014.
%Y A076015 A diagonal of array A103438.
%Y A076015 A subset of A000312.
%K A076015 nonn,easy
%O A076015 1,2
%A A076015 _Wolfdieter Lang_, Oct 02 2002
%E A076015 Definition changed and example added by _Olivier Gérard_, Jan 28 2023