A229140 - OEIS

A229140

Smallest k such that k^2 + l^2 = n-th number expressible as sum of two squares (A001481).

0, 0, 1, 0, 1, 2, 0, 1, 2, 0, 1, 3, 2, 0, 1, 2, 4, 3, 0, 1, 2, 4, 3, 0, 1, 4, 2, 3, 5, 0, 1, 2, 6, 3, 5, 4, 0, 1, 2, 5, 3, 4, 7, 0, 1, 2, 5, 3, 7, 4, 6, 0, 1, 2, 8, 3, 6, 4, 0, 1, 5, 2, 7, 3, 6, 4, 9, 8, 0, 1, 2, 3, 6, 9, 4, 7, 5, 0, 1, 2, 9, 3, 8, 4, 7, 5, 0

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OFFSET

1,6

COMMENTS

a(n) = 0 if A001481(n) is square. Conjecture: the values between two zeros are always distinct from each other.

LINKS

Table of n, a(n) for n=1..87.

EXAMPLE

The 6th number expressible as sum of two squares A001481(6) = 8 = 2^2 + 2^2, so a(6)=2.

PROG

(PARI) for(n=1, 300, s=sqrtint(n); forstep(i=s, 1, -1, if(issquare(n-i*i), print1(sqrtint(n-i*i), ", "); break)))

CROSSREFS