A004439 Numbers that are not the sum of 2 distinct nonzero squares.

1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 14, 15, 16, 18, 19, 21, 22, 23, 24, 27, 28, 30, 31, 32, 33, 35, 36, 38, 39, 42, 43, 44, 46, 47, 48, 49, 51, 54, 55, 56, 57, 59, 60, 62, 63, 64, 66, 67, 69, 70, 71, 72, 75, 76, 77, 78, 79

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Links

• Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
• F. Smarandache, Definitions, Solved and Unsolved Problems, Conjectures, ..., edited by M. Perez, Xiquan Publishing House, 2000.
• Index entries for sequences related to sums of squares

Crossrefs

Complement of A004431.

Programs

PARI

is(n)=if(n<5, return(1)); my(f=factor(n)%4); if(vecmin(f[,1])>1, return(1)); for(i=1,#f[,1], if(f[i,1]==3 && f[i,2]%2, return(1))); 0 \\ Charles R Greathouse IV, Jun 18 2013