cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-6 of 6 results.

A025333 Numbers that are the sum of 3 nonzero squares in 5 or more ways.

Original entry on oeis.org

194, 206, 209, 230, 266, 269, 281, 297, 306, 314, 321, 326, 329, 341, 342, 350, 354, 369, 374, 381, 386, 389, 398, 401, 402, 413, 414, 419, 425, 426, 434, 437, 441, 446, 449, 450, 458, 459, 461, 470, 474, 482, 486, 489, 491, 494, 497, 506, 509, 513, 521, 525, 530, 531
Offset: 1

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Crossrefs

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

Original entry on oeis.org

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

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Crossrefs

Programs

  • 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

Formula

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

A343987 Numbers that are the sum of four positive cubes in five or more ways.

Original entry on oeis.org

5105, 5131, 5616, 5859, 6435, 6883, 7777, 9315, 9737, 9793, 10017, 10250, 10458, 10936, 10962, 11000, 11060, 11088, 11592, 11664, 11781, 12168, 12229, 12285, 12320, 12385, 12392, 12411, 12707, 13104, 13384, 13734, 13832, 13904, 13923, 14112, 14183, 14239, 14581, 14833, 14896, 14904, 15176, 15561, 15596
Offset: 1

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Author

David Consiglio, Jr., May 06 2021

Keywords

Examples

			5616 = 1^3 + 8^3 + 12^3 + 15^3
     = 2^3 + 8^3 + 10^3 + 16^3
     = 4^3 + 4^3 + 14^3 + 14^3
     = 4^3 + 5^3 + 11^3 + 16^3
     = 8^3 + 9^3 + 10^3 + 15^3
so 5616 is a term.
		

Crossrefs

Programs

  • Python
    from itertools import combinations_with_replacement as cwr
    from collections import defaultdict
    keep = defaultdict(lambda: 0)
    power_terms = [x ** 3 for x in range(1, 50)]
    for pos in cwr(power_terms, 4):
        tot = sum(pos)
        keep[tot] += 1
    rets = sorted([k for k, v in keep.items() if v >= 5])
    for x in range(len(rets)):
        print(rets[x], end=", ")

A344798 Numbers that are the sum of five squares in five or more ways.

Original entry on oeis.org

53, 56, 59, 61, 64, 67, 68, 74, 77, 79, 80, 83, 85, 86, 88, 91, 92, 93, 94, 95, 96, 98, 99, 100, 101, 102, 103, 104, 106, 107, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 130, 131, 133, 134, 135, 136, 137
Offset: 1

Views

Author

Sean A. Irvine, May 28 2021

Keywords

Crossrefs

A025369 Numbers that are the sum of 4 nonzero squares in 4 or more ways.

Original entry on oeis.org

52, 58, 63, 70, 76, 82, 84, 87, 90, 91, 93, 97, 98, 100, 102, 103, 105, 106, 108, 111, 114, 115, 117, 118, 119, 122, 123, 124, 126, 127, 130, 132, 133, 135, 138, 139, 140, 141, 142, 143, 145, 146, 147, 148, 150, 151, 153, 154, 155, 156, 157, 158, 159, 162, 163, 165, 166
Offset: 1

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Crossrefs

Formula

{n: A025428(n) >= 4}. Union of A025370 and A025360. - R. J. Mathar, Jun 15 2018

A025389 Numbers that are the sum of 4 distinct nonzero squares in 5 or more ways.

Original entry on oeis.org

126, 150, 170, 174, 186, 190, 198, 210, 219, 222, 225, 230, 231, 234, 238, 242, 246, 249, 250, 254, 255, 258, 261, 266, 267, 270, 273, 274, 275, 278, 279, 282, 285, 286, 287, 290, 291, 294, 295, 297, 302, 303, 305, 306, 309, 310, 311, 314, 315, 318, 319, 321, 322, 323
Offset: 1

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Author

Keywords

Crossrefs

Cf. A025370.

Formula

{n: A025443(n) >= 5}. Union of A025390 and A025380. - R. J. Mathar, Jun 15 2018
Showing 1-6 of 6 results.