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

Author

Hugo Pfoertner, Aug 01 2023

Keywords

• nonn

Crossrefs

Cf. A004215, A077773, A364445.

Programs

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