A176209 Numbers that can be greedily decomposed as a sum of two or more squares >= 4.

8, 13, 20, 24, 29, 33, 34, 40, 44, 45, 53, 57, 58, 62, 68, 72, 73, 77, 80, 85, 89, 90, 94, 97, 104, 108, 109, 113, 116, 120, 125, 129, 130, 134, 137, 141, 148, 152, 153, 157, 160, 164, 168, 173, 177, 178, 182, 185, 189, 193, 194, 200, 204, 205, 209, 212, 216, 220

Offset

1,1

Links

Daniel Mondot, Table of n, a(n) for n = 1..10000

Example

8 = 4+4, 13 = 9+4, 20 = 16+4, 24 = 16+4+4, 29 = 25+4, ...

Mathematica

f1[n_]:=(x=n; While[x>3, x-=Floor[Sqrt[x]]^2]; x); f2[n_]:=(x=n; k=0; While[x>3, k++; x-=Floor[Sqrt[x]]^2]; k); lst={}; Do[If[f1[n]==0&&f2[n]>1, AppendTo[lst, n]], {n, 6!}]; lst

Prog

(C)
#include <stdio.h>
#include <math.h>
void main()
{
  unsigned int a, n, i, j, k;
  for (n=0, a=1; n<10000; ++a)
  {
    for (i=a, j=0; i>=4; ++j) { k=sqrt(i); i -= k*k; }
    if ((i==0) && (j>=2)) printf("%u %u\n", ++n, a);
  }
} // Daniel Mondot, Jan 20 2026

Crossrefs

Cf. A000290.

Sequence in context: A070131 A030782 A219721 * A227453 A266212 A063849

Adjacent sequences: A176206 A176207 A176208 * A176210 A176211 A176212

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, Apr 12 2010

Extensions

Changed sequence name to reflect the definition by Robin Houston, Jan 22 2026

Status

approved