A054402 Numbers that are the sum of a positive square and a positive cube in more than one way.

17, 65, 89, 108, 129, 145, 225, 233, 252, 297, 316, 388, 449, 464, 505, 537, 548, 577, 593, 633, 730, 737, 745, 792, 793, 801, 873, 1025, 1088, 1090, 1116, 1289, 1304, 1305, 1367, 1412, 1441, 1452, 1529, 1585, 1601

Offset

1,1

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Example

a(1)=17 since 17 = 3^2 + 2^3 = 4^2 + 1^3.

Mathematica

lst={}; Do[Do[AppendTo[lst, n^2+m^3], {n, 5!}], {m, 5!}]; lst=Sort[lst]; lst2={}; Do[If[lst[[n]]==lst[[n+1]], AppendTo[lst2, lst[[n]]]], {n, Length[lst]-1}]; lst2; Take[Union[lst2], 123] (* Vladimir Joseph Stephan Orlovsky, Jul 17 2009 *)

Prog

(PARI) list(lim)=my(v=List(), u=List()); for(n=1, sqrtint(lim\1-1), for(m=1, sqrtnint(lim\1-n^2, 3), listput(v, n^2+m^3))); v=vecsort(v); for(i=2, #v, if(v[i]==v[i-1], listput(u, v[i]))); Set(u) \\ Charles R Greathouse IV, May 15 2015

Crossrefs

Cf. A055393, A055394.

Sequence in context: A145850 A125992 A363714 * A086533 A226685 A108211

Adjacent sequences: A054399 A054400 A054401 * A054403 A054404 A054405

Keyword

easy,nonn

Author

Henry Bottomley, May 12 2000

Status

approved