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%I #37 Sep 07 2023 12:47:33
%S 0,1,55,91,208335
%N Numbers that are simultaneously triangular and square pyramidal.
%C Equivalent to 0^2 + 1^2 + 2^2 + 3^2 + ... + r^2 = 0 + 1 + 2 + 3 + ... + s = n for some r and s.
%D Joe Roberts, Lure of the Integers, page 245 (entry for 645).
%D David Wells, The Penguin Dictionary of Curious and Interesting Numbers, Penguin Books, p. 108.
%H R. Finkelstein and H. London, <a href="http://dx.doi.org/10.1016/0022-314X(72)90036-4">On triangular numbers which are sums of consecutive squares</a>, J. Number Theory 4 (1972), 455-462.
%H M. Gardner, <a href="/A001110/a001110.jpg">Letter to N. J. A. Sloane, circa Aug 11 1980</a>, concerning A001110, A027568, A039596, etc.
%H H. E. Thomas Jr., <a href="http://www.jstor.org/stable/2315561">Problem 5634</a>, Amer. Math. Monthly, 75 (1968), p. 1018.
%e 1^2 + 2^2 + 3^2 + 4^2 + 5^2 = 1 + 2 + 3 + ... + 10 = 55, so 55 is in the sequence.
%Y Intersection of A000217 and A000330.
%Y Cf. A053611, A053612.
%K fini,nonn,full
%O 1,3
%A _Felice Russo_
%E Additional comments from _Jud McCranie_, Mar 19 2000
%E Zero inserted by _Daniel Mondot_, Sep 07 2023
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