A364444 a(n) is the number of integers k with n^2 < k < (n+1)^2 that are the sum of no more than 3 squares, counting multiple representations only once.

0, 2, 3, 5, 7, 8, 10, 11, 14, 15, 16, 18, 20, 22, 23, 24, 27, 29, 30, 31, 34, 34, 36, 38, 40, 42, 44, 44, 47, 48, 49, 51, 54, 55, 57, 58, 61, 61, 62, 65, 67, 69, 69, 71, 73, 75, 76, 78, 81, 81, 83, 85, 87, 89, 89, 91, 94, 95, 97, 97, 100, 101, 103, 104, 107, 109

Offset

0,2

Links

Table of n, a(n) for n=0..65.

Prog

(PARI) isA004215(n)= n\4^valuation(n, 4)%8==7 \\ after M. F. Hasler
a364444(n) = sum (k=n^2+1, n^2+2*n, !isA004215(k))
(Python)
def A364444(n): return sum(1 for k in range(n**2+1, (n+1)**2) if (m:=(~k&k-1).bit_length())&1 or (k>>m)&7<7) # Chai Wah Wu, Aug 01 2023

Crossrefs

Cf. A004215, A077773, A364445.

Sequence in context: A022342 A218606 A077164 * A062132 A003258 A028738

Adjacent sequences: A364441 A364442 A364443 * A364445 A364446 A364447

Keyword

nonn

Author

Hugo Pfoertner, Aug 01 2023

Status

approved