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 1-9 of 9 results.

A001422 Numbers which are not the sum of distinct squares.

Original entry on oeis.org

2, 3, 6, 7, 8, 11, 12, 15, 18, 19, 22, 23, 24, 27, 28, 31, 32, 33, 43, 44, 47, 48, 60, 67, 72, 76, 92, 96, 108, 112, 128
Offset: 1

Views

Author

N. J. A. Sloane, Jeff Adams (jeff.adams(AT)byu.net)

Keywords

Comments

This is the complete list (Sprague).

References

  • S. Lin, Computer experiments on sequences which form integral bases, pp. 365-370 of J. Leech, editor, Computational Problems in Abstract Algebra. Pergamon, Oxford, 1970.
  • Harry L. Nelson, The Partition Problem, J. Rec. Math., 20 (1988), 315-316.
  • J. Roberts, Lure of the Integers, Math. Assoc. America, 1992, p. 222.

Crossrefs

Complement of A003995. Subsequence of A004441.
Cf. A025524 (number of numbers not the sum of distinct n-th-order polygonal numbers)
Cf. A007419 (largest number not the sum of distinct n-th-order polygonal numbers)
Cf. A053614, A121405 (corresponding sequences for triangular and pentagonal numbers)
Cf. A001476, A046039, A194768, A194769 for 3rd, 4th, 5th, 6th powers.
Cf. A001661.

Programs

  • Mathematica
    nn=50; t=Rest[CoefficientList[Series[Product[(1+x^(k*k)), {k,nn}], {x,0,nn*nn}], x]]; Flatten[Position[t,0]] (* T. D. Noe, Jul 24 2006 *)
  • PARI
    select( is_A001422(n,m=n)={m^2>n&& m=sqrtint(n); n!=m^2&&!while(m>1,isSumOfSquares(n-m^2,m--)&&return)}, [1..128]) \\ M. F. Hasler, Apr 21 2020

A276516 Expansion of Product_{k>=1} (1-x^(k^2)).

Original entry on oeis.org

1, -1, 0, 0, -1, 1, 0, 0, 0, -1, 1, 0, 0, 1, -1, 0, -1, 1, 0, 0, 1, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1, -1, 1, -1, 1, 1, 0, -1, 0, 0, 0, 0, 0, 0, -2, 1, 1, 1, 0, 0, -1, -1, 1, 1, -1, 0, 0, -1, 1, -1, 2, -1, 0, 1, -2, 0, 1, 0, 1, 0, -1, 0, -2, 2, 0
Offset: 0

Views

Author

Vaclav Kotesovec, Dec 12 2016

Keywords

Comments

The difference between the number of partitions of n into an even number of distinct squares and the number of partitions of n into an odd number of distinct squares. - Ilya Gutkovskiy, Jan 15 2018

Crossrefs

Programs

  • Mathematica
    nn = 15; CoefficientList[Series[Product[(1-x^(k^2)), {k, nn}], {x, 0, nn^2}], x]
    nmax = 200; nn = Floor[Sqrt[nmax]]+1; poly = ConstantArray[0, nn^2 + 1]; poly[[1]] = 1; poly[[2]] = -1; poly[[3]] = 0; Do[Do[poly[[j + 1]] -= poly[[j - k^2 + 1]], {j, nn^2, k^2, -1}];, {k, 2, nn}]; Take[poly, nmax+1]

Formula

a(n) = Sum_{k>=0} (-1)^k * A341040(n,k). - Alois P. Heinz, Feb 03 2021
a(n) = A033461(n) - 2*A339367(n). - R. J. Mathar, Jul 29 2025

A279486 Indices k such that A279484(k) = 0.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 29, 30, 31, 32, 33, 34, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 66, 67, 68, 69, 70, 71, 74, 75, 76, 77
Offset: 1

Views

Author

Vaclav Kotesovec, Dec 13 2016

Keywords

Comments

This is different from A001476, first difference: a(450) = 540, A001476(450) = 542.
Conjecture: for k > 353684 there are no more terms in this sequence (tested for k < 1000000).

Examples

			3 is in the sequence because A279484(3) = 0
8 is not in the sequence because A279484(8) = -1
344739 is in the sequence because A279484(344739) = 0
353684 is in the sequence because A279484(353684) = 0
		

Crossrefs

Programs

  • Mathematica
    nn = 10; A279484 = Rest[CoefficientList[Series[Product[(1-x^(k^3)), {k, nn}], {x, 0, nn^3}], x]]; Select[Range[nn^3], A279484[[#]]==0&]
    nmax = 1000; nn = Floor[nmax^(1/3)]+1; poly = ConstantArray[0, nn^3 + 1]; poly[[1]] = 1; poly[[2]] = -1; poly[[3]] = 0; Do[Do[poly[[j + 1]] -= poly[[j - k^3 + 1]], {j, nn^3, k^3, -1}];, {k, 2, nn}]; A279484 = Take[poly, {2, nmax+1}]; Select[Range[nmax], A279484[[#]]==0&]

A279487 Indices k such that A279485(k) = 0.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70
Offset: 1

Views

Author

Vaclav Kotesovec, Dec 13 2016

Keywords

Comments

This is different from A046039, first difference: a(14328) = 14979, A046039(14328) = 14981.
Conjecture: Last term is a(1040799) = 64674419. For k > 64674419 there are no more terms in this sequence (tested for k < 150000000).
Last terms are: 30082710, 30345655, 30358709, 30530388, 30982210, 31463972, 32369456, 32374194, 32594966, 32658048, 32780596, 32875172, 32997892, 33135812, 33440935, 33647428, 34086978, 34112787, 34629875, 35535908, 35638453, 36081828, 36140868, 36945332, 39218566, 39581363, 40364547, 40491526, 41235157, 43853600, 47973011, 57353782, 57767766, 64674419

Examples

			3 is in the sequence because A279485(3) = 0
16 is not in the sequence because A279485(16) = -1
57767766 is in the sequence because A279485(57767766) = 0
64674419 is in the sequence because A279485(64674419) = 0
		

Crossrefs

Programs

  • Mathematica
    nn = 10; A279485 = Rest[CoefficientList[Series[Product[(1-x^(k^4)), {k, nn}], {x, 0, nn^4}], x]]; Select[Range[nn^4], A279485[[#]]==0&]
    nmax = 10000; nn = Floor[nmax^(1/4)]+1; poly = ConstantArray[0, nn^4 + 1]; poly[[1]] = 1; poly[[2]] = -1; poly[[3]] = 0; Do[Do[poly[[j + 1]] -= poly[[j - k^4 + 1]], {j, nn^4, k^4, -1}];, {k, 2, nn}]; A279485 = Take[poly, {2, nmax+1}]; Select[Range[nmax], A279485[[#]]==0&]

A292740 Indices k such that A292547(k) = 0.

Original entry on oeis.org

2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 22 2017

Keywords

Comments

Complement of A290276.
Conjecture: for k > 212594 there are no more terms in this sequence (tested for k < 63000000).

Examples

			3 is in the sequence because A292547(3) = 0
8 is not in the sequence because A292547(8) = -1
201254 is in the sequence because A292547(201254) = 0
212594 is in the sequence because A292547(212594) = 0
		

Crossrefs

Programs

  • Mathematica
    With[{nn = 200}, -1 + Position[#, 0][[All, 1]] &@ CoefficientList[ Series[Product[1 + x^((2 k - 1)^3), {k, 1, Floor[nn^(1/3)/2] + 1}], {x, 0, nn}], x]] (* Michael De Vlieger, Sep 22 2017, after Vaclav Kotesovec at A292547 *)

A279529 a(n) is a largest m such that coefficient [x^m] in Product_{k>=1} (1-x^(k^n)) is equal to zero.

Original entry on oeis.org

7169, 353684, 64674419
Offset: 2

Views

Author

Vaclav Kotesovec, Dec 14 2016

Keywords

Examples

			a(2) = 7169 because A276516(7169) = 0 and A276516(m) <> 0 for m > 7169.
a(3) = 353684 because A279484(353684) = 0 and A279484(m) <> 0 for m > 353684.
a(4) = 64674419 because A279485(64674419) = 0 and A279485(m) <> 0 for m > 64674419.
a(2) = A276517(173) = 7169.
a(3) = A279486(5216) = 353684.
a(4) = A279487(1040799) = 64674419.
		

Crossrefs

A304028 Numbers k such that A033461(k) is divisible by k.

Original entry on oeis.org

1, 2, 3, 6, 7, 8, 11, 12, 15, 18, 19, 22, 23, 24, 27, 28, 31, 32, 33, 43, 44, 47, 48, 60, 67, 72, 76, 92, 96, 108, 112, 128, 2229, 2929, 3022, 4481, 34542, 34951, 36996, 58091, 292949, 437728, 438237, 2103581, 2237158, 3215950, 3375578
Offset: 1

Views

Author

Vaclav Kotesovec, May 04 2018

Keywords

Comments

A001422 is a finite subsequence.

Examples

			2229 is in the sequence because A033461(2229) = 51267 = 23 * 2229.
		

Crossrefs

Programs

  • Mathematica
    max = 100; p = ConstantArray[0, max^2 + 1]; p[[1]] = 1; p[[2]] = 1; Do[Do[p[[j + 1]] += p[[j - k^2 + 1]], {j, max^2, k^2, -1}];, {k, 2, max}]; Select[Range[1, max^2], Divisible[p[[# + 1]], #] &]

A305440 Indices k such that A292518(k) = 0.

Original entry on oeis.org

2, 5, 8, 12, 21, 22, 23, 24, 33, 36, 45, 46, 48, 50, 67, 72, 75, 78, 85, 86, 88, 91, 92, 107, 111, 112, 121, 130, 139, 149, 156, 158, 161, 170, 180, 189, 193, 196, 200, 205, 224, 225, 230, 242, 270, 291, 305, 341, 369, 386, 387, 394, 397, 403, 426, 459, 475, 493, 521, 603, 666, 750
Offset: 1

Views

Author

Seiichi Manyama, Jun 01 2018

Keywords

Comments

Conjecture: for k > 3957 there are no more terms in this sequence.

Examples

			   2 is in the sequence because A292518(   2) = 0.
3957 is in the sequence because A292518(3957) = 0.
		

Crossrefs

A305441 Indices k such that A305355(k) = 0.

Original entry on oeis.org

2, 3, 4, 7, 8, 9, 10, 11, 14, 15, 16, 19, 20, 21, 24, 25, 26, 29, 30, 31, 32, 33, 37, 38, 42, 43, 44, 45, 46, 49, 50, 52, 54, 55, 57, 59, 60, 61, 65, 66, 67, 69, 70, 72, 74, 75, 77, 80, 81, 84, 89, 93, 94, 95, 96, 97, 100, 101, 102, 107, 112, 114, 116, 121, 124, 128
Offset: 1

Views

Author

Seiichi Manyama, Jun 01 2018

Keywords

Comments

Conjecture: for k > 10316 there are no more terms in this sequence.

Examples

			    2 is in the sequence because A305355(    2) = 0.
10316 is in the sequence because A305355(10316) = 0.
		

Crossrefs

Showing 1-9 of 9 results.