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 1-4 of 4 results.

A290334 Numbers that are not the sum of three or fewer terms from A020330.

Original entry on oeis.org

1, 2, 4, 5, 7, 8, 11, 12, 14, 17, 19, 22, 24, 26, 27, 29, 31, 32, 34, 37, 38, 41, 43, 44, 47, 50, 52, 53, 59, 62, 68, 71, 77, 80, 85, 86, 89, 92, 94, 95, 97, 98, 101, 103, 104, 106, 107, 110, 112, 113, 115, 116, 119, 121, 122, 124, 125, 128, 130, 131, 133, 134, 137, 138, 140, 143, 145, 147, 148, 150, 152, 155, 157, 158, 160, 164, 165
Offset: 1

Views

Author

Jeffrey Shallit, Jul 27 2017

Keywords

Comments

Not currently proved that there are infinitely many terms. It is conjectured that all integers > 686 are the sum of four binary squares.

Crossrefs

Programs

  • Mathematica
    v = Table[n + n * 2^Floor[Log2[n] + 1], {n, 0, 12}]; Complement[Range[v[[-1]]], Plus @@@ Tuples[v, 3]] (* Amiram Eldar, Apr 09 2021 *)

A298731 Number of distinct representations of n as a sum of four terms of A020330 (including 0), where order does not matter.

Original entry on oeis.org

1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 1, 1, 0, 1, 0, 2, 1, 0, 2, 0, 1, 2, 0, 1, 1, 2, 0, 1, 1, 0, 4, 1, 0, 2, 1, 1, 2, 1, 0, 3, 2, 1, 2, 1, 1, 3, 2, 0, 3, 2, 1, 4, 1, 1, 3, 2, 1, 3, 2, 1, 4, 2, 1, 3, 2, 1, 3, 2, 1, 4, 2, 1, 3, 1, 1, 4, 2, 1, 4, 2, 0, 4, 1, 1, 4, 2, 1, 3, 3, 0, 4, 1
Offset: 0

Views

Author

Jeffrey Shallit, Jan 25 2018

Keywords

Examples

			For n = 45, the a(45) = 4 solutions are 45 = 15+15+15 = 36+3+3+3 = 15+10+10+10.
		

Crossrefs

Cf. A020330, A290334, A290335 (which is the same sequence where order matters).

Programs

  • Mathematica
    v = Table[k + k * 2^Floor[Log2[k] + 1], {k, 0, 8}]; a[n_] := Length @ IntegerPartitions[n, {4}, v]; Table[a[n], {n, 0, v[[-1]]}] (* Amiram Eldar, Apr 09 2021 *)

A343268 Numbers that are not the sum of exactly four terms from A020330 (not necessarily distinct).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 25, 27, 28, 29, 30, 32, 34, 35, 37, 39, 41, 42, 44, 46, 47, 49, 51, 53, 56, 58, 62, 65, 67, 74, 83, 88, 95, 100, 104, 107, 109, 113, 116, 122, 125, 131, 134, 140, 143, 148, 149, 155
Offset: 1

Views

Author

Amiram Eldar, Apr 09 2021

Keywords

Comments

Madhusudan et al. (2018) conjectured that a(112) = 1772 is the last term of this sequence.

Crossrefs

Programs

  • Mathematica
    v = Table[n + n * 2^Floor[Log2[n] + 1], {n, 1, 31}]; Complement[Range[0, 2000], Plus @@@ Tuples[v, 4]]

A343267 Numbers that are not the sum of four or fewer terms from A020330 (not necessarily distinct).

Original entry on oeis.org

1, 2, 4, 5, 7, 8, 11, 14, 17, 22, 27, 29, 32, 34, 37, 41, 44, 47, 53, 62, 95, 104, 107, 113, 116, 122, 125, 131, 134, 140, 143, 148, 155, 158, 160, 167, 407, 424, 441, 458, 475, 492, 509, 526, 552, 560, 569, 587, 599, 608, 613, 620, 638, 653, 671, 686
Offset: 1

Views

Author

Amiram Eldar, Apr 09 2021

Keywords

Comments

Madhusudan et al. (2018) proved that a(56) = 686 is the last term of this sequence.

Crossrefs

Programs

  • Mathematica
    v = Table[n + n * 2^Floor[Log2[n] + 1], {n, 0, 20}]; Complement[Range[0, 700], Plus @@@ Tuples[v, 4]]
Showing 1-4 of 4 results.