A025371 Numbers that are the sum of 4 nonzero squares in 6 or more ways.

90, 124, 130, 133, 135, 138, 147, 148, 150, 154, 156, 157, 159, 162, 163, 165, 166, 170, 171, 172, 174, 175, 177, 178, 180, 182, 183, 186, 187, 188, 189, 190, 193, 195, 196, 198, 199, 201, 202, 203, 205, 207, 210, 213, 214, 215, 217, 218, 219, 220, 222, 223, 225, 226

Offset

1,1

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Index entries for sequences related to sums of squares

Formula

{n: A025428(n) >= 6}. Union of A025372 and A025362. - R. J. Mathar, Jun 15 2018

Prog

(Python)
limit = 226
from functools import lru_cache
sq = [k**2 for k in range(1, int(limit**.5)+2) if k**2 + 3 <= limit]
sqs = set(sq)
@lru_cache(maxsize=None)
def findsums(n, m):
  if m == 1: return {(n, )} if n in sqs else set()
  return set(tuple(sorted(t+(s, ))) for s in sqs for t in findsums(n-s, m-1))
print([n for n in range(4, limit+1) if len(findsums(n, 4)) >= 6]) # Michael S. Branicky, Apr 20 2021

Crossrefs

Cf. A025334, A025362, A025370, A025372, A344799, A345148.

Sequence in context: A078493 A176683 A135197 * A025362 A114826 A332725

Adjacent sequences: A025368 A025369 A025370 * A025372 A025373 A025374

Keyword

nonn

Author

David W. Wilson

Status

approved