A171385 Sum of a positive square and a positive cube in at least three ways.

1025, 1737, 2089, 2628, 2817, 3033, 3664, 4481, 4825, 4977, 5841, 7057, 7785, 7948, 8225, 8289, 8900, 10025, 11025, 11665, 12393, 14049, 14400, 14724, 15193, 15345, 15641, 15689, 15884, 16649, 16857, 18201, 18369, 19225, 19664, 19908, 20224

Offset

1,1

Comments

Four or more representations have 1025, 19225, 27289, 29025, 39329, 48025, 54225, 65537, 65600, 79129, 92025, 93241, 105192, 105633, 111681, ... - R. J. Mathar, Dec 11 2009

Links

Table of n, a(n) for n=1..37.

Example

1025 = 32^2 + 1^3, 31^2 + 4^3, 30^2 + 5^3, and 5^2 + 10^3;
1737 = 35^2 + 8^3, 3^2 + 12^3, and 39^2 + 6^3.

Maple

isA171385 := proc(n) a := 0 ; for c from 1 do if c^3 >= n then break; else if issqr(n-c^3) then a := a+1 ; end if; end if; end do ; a >= 3 ; end proc: for n from 2 to 120000 do if isA171385(n) then printf("%d, ", n) ; fi; end do ; # R. J. Mathar, Dec 11 2009

Crossrefs

Cf. A054402, integers with two or more such representations.

Sequence in context: A351310 A045035 A060948 * A031742 A353943 A351273

Adjacent sequences: A171382 A171383 A171384 * A171386 A171387 A171388

Keyword

easy,nonn

Author

Alan Frank, Dec 07 2009

Extensions

More terms from R. J. Mathar, Dec 11 2009

Status

approved