cp's OEIS Frontend

A216640 Number of nondecreasing arrays of n 1..n integers with the sum of their 2nd powers equal to sum(i^2,i=1..n).

%I A216640 #9 Jun 02 2025 08:07:53
%S A216640 1,1,1,1,1,3,8,25,83,257,788,2491,7885,25099,80481,264505,884517,
%T A216640 2994535,10208806,35095825,121699761,424273761,1487693075,5244197347,
%U A216640 18584820912,66169376686,236592018517,849466213882,3061492852986,11072927827447
%N A216640 Number of nondecreasing arrays of n 1..n integers with the sum of their 2nd powers equal to sum(i^2,i=1..n).
%C A216640 Column 2 of A216645
%H A216640 R. H. Hardin, <a href="/A216640/b216640.txt">Table of n, a(n) for n = 1..49</a>
%e A216640 All solutions for n=6
%e A216640 ..1....3....1
%e A216640 ..2....3....1
%e A216640 ..3....4....1
%e A216640 ..4....4....4
%e A216640 ..5....4....6
%e A216640 ..6....5....6
%K A216640 nonn
%O A216640 1,6
%A A216640 _R. H. Hardin_ Sep 11 2012