A212795 Sums of squares of two distinct nonzero triangular numbers, i.e., of the form A000217(m)^2+A000217(n)^2, m>n>0.

10, 37, 45, 101, 109, 136, 226, 234, 261, 325, 442, 450, 477, 541, 666, 785, 793, 820, 884, 1009, 1225, 1297, 1305, 1332, 1396, 1521, 1737, 2026, 2034, 2061, 2080, 2125, 2250, 2466, 2809, 3026, 3034, 3061, 3125, 3250, 3321, 3466

Offset

1,1

Comments

From a(28) on, terms are no more in the lexicographic order of increasing (m, n).

Links

Table of n, a(n) for n=1..42.

Example

A000217 = (0, 1, 3, 6, ...), thus
a(1)=3^2+1^2, a(2)=6^2+1^2, a(3)=6^2+3^2, ...,
a(28)=45^2+1^2, ..., a(31)=36^2+28^2.

Mathematica

With[{nn=50}, Take[Union[Total/@Subsets[Accumulate[Range[nn]]^2, {2}]], nn]] (* Harvey P. Dale, Sep 24 2016 *)

Prog

(PARI) vecsort(select(concat(vector(10, i, vector(i-1, j, A000217(i)^2+ A000217(j)^2))), x->x<11^4/4))

Crossrefs

A subsequence of A004431.

Sequence in context: A089222 A139242 A139236 * A227695 A247792 A372373

Adjacent sequences: A212792 A212793 A212794 * A212796 A212797 A212798

Keyword

nonn

Author

M. F. Hasler, May 27 2012

Status

approved