A339977 Sums of two distinct odd squares.

10, 26, 34, 50, 58, 74, 82, 90, 106, 122, 130, 146, 170, 178, 194, 202, 218, 226, 234, 250, 274, 290, 298, 306, 314, 338, 346, 362, 370, 386, 394, 410, 442, 450, 458, 466, 482, 490, 514, 522, 530, 538, 554, 562, 578, 586, 610, 626, 634, 650, 666, 674, 698, 706, 730, 738

Offset

1,1

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Formula

a(n) == 2 (mod 8). - Hugo Pfoertner, Mar 29 2021

Example

26 is in the sequence since it is the sum of two distinct odd squares as 1^2 + 5^2 = 1 + 25 = 26.

Mathematica

Table[If[Sum[Mod[i, 2] Mod[n - i, 2] (Floor[Sqrt[i]] - Floor[Sqrt[i - 1]]) (Floor[Sqrt[n - i]] - Floor[Sqrt[n - i - 1]]), {i, Floor[(n - 1)/2]}] > 0, n, {}], {n, 800}] // Flatten

Prog

(Python)
def aupto(limit):
    s = [i*i for i in range(1, limit//2+1, 2) if i*i < limit]
    s2 = set(a+b for i, a in enumerate(s) for b in s[i+1:] if a+b <= limit)
    return sorted(s2)
print(aupto(738)) # Michael S. Branicky, Oct 26 2021

Crossrefs

Cf. A010052, A016754, A004431.

Sequence in context: A023715 A045143 A005278 * A157075 A369668 A262998

Adjacent sequences: A339974 A339975 A339976 * A339978 A339979 A339980

Keyword

nonn

Author

Wesley Ivan Hurt, Dec 25 2020

Status

approved