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.

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A319935 T(n,k) = [x^n] JacobiTheta3(0,x)^k, for 0 <= k <= n, triangle read by rows.

Original entry on oeis.org

1, 0, 2, 0, 0, 4, 0, 0, 0, 8, 0, 2, 4, 6, 24, 0, 0, 8, 24, 48, 112, 0, 0, 0, 24, 96, 240, 544, 0, 0, 0, 0, 64, 320, 960, 2368, 0, 0, 4, 12, 24, 200, 1020, 3444, 9328, 0, 2, 4, 30, 104, 250, 876, 3542, 12112, 34802, 0, 8, 24, 144, 560, 1560, 4424, 14112, 44640, 129064, 339064
Offset: 0

Views

Author

Peter Luschny, Oct 06 2018

Keywords

Examples

			Triangle starts:
[0] 1
[1] 0, 2
[2] 0, 0, 4
[3] 0, 0, 0,  8
[4] 0, 2, 4,  6,  24
[5] 0, 0, 8, 24,  48, 112
[6] 0, 0, 0, 24,  96, 240,  544
[7] 0, 0, 0,  0,  64, 320,  960, 2368
[8] 0, 0, 4, 12,  24, 200, 1020, 3444,  9328
[9] 0, 2, 4, 30, 104, 250,  876, 3542, 12112, 34802
		

Crossrefs

T(n,n) = A066535(n), row sums A320025.

Programs

  • Maple
    A319935row := proc(n) local ser;
    ser := j -> series(JacobiTheta3(0, x)^j, x, n+1);
    seq(coeff(ser(j), x, n), j=0..n) end:
    seq(A319935row(n), n=0..10);

A294071 Number of ordered ways of writing n^2 as a sum of n squares > 1.

Original entry on oeis.org

1, 0, 0, 0, 1, 5, 6, 7, 288, 262, 13702, 69531, 610567, 5356091, 51724960, 521956086, 5467658641, 59931636545, 690518644584, 8100858045744, 99142980567486, 1246972499954475, 16142015005905558, 215722810653380845, 2955759897694815985, 41614888439136252691
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 07 2018

Keywords

Examples

			a(5) = 5 because we have [9, 4, 4, 4, 4], [4, 9, 4, 4, 4], [4, 4, 9, 4, 4], [4, 4, 4, 9, 4] and [4, 4, 4, 4, 9].
		

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[((-1 - 2 x + EllipticTheta[3, 0, x])/2)^n, {x, 0, n^2}], {n, 0, 25}]

Formula

a(n) = [x^(n^2)] (Sum_{k>=2} x^(k^2))^n.

A319221 Number of ordered ways of writing n-th triangular number as a sum of n squares.

Original entry on oeis.org

1, 2, 0, 24, 144, 960, 4608, 74048, 859952, 9568800, 109975680, 1647979872, 23917274304, 358378620704, 5528847787008, 94307761212304, 1632598198916544, 29205907283227776, 538335591996965760, 10388234139989630128, 205386383159397554688, 4173254005731822569088
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 13 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[EllipticTheta[3, 0, x]^n, {x, 0, n (n + 1)/2}], {n, 0, 21}]
    Join[{1}, Table[SquaresR[n, n (n + 1)/2], {n, 21}]]

Formula

a(n) = [x^(n*(n+1)/2)] theta_3(x)^n, where theta_3() is the Jacobi theta function.
a(n) = [x^(n*(n+1)/2)] (Sum_{k=-infinity..infinity} x^(k^2))^n.

A319223 Number of ordered ways of writing n^3 as a sum of n squares.

Original entry on oeis.org

1, 2, 4, 32, 24, 14112, 674368, 39801344, 2454266992, 166591027058, 12820702401872, 1156778646258336, 119773060481140800, 14004241350957965408, 1791476464655904407168, 247572699435320047056384, 36696694077934168215974368, 5825316759916541565549586176, 989291135292653632945527984868
Offset: 0

Views

Author

Ilya Gutkovskiy, Sep 13 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[EllipticTheta[3, 0, x]^n, {x, 0, n^3}], {n, 0, 18}]
    Join[{1}, Table[SquaresR[n, n^3], {n, 18}]]

Formula

a(n) = [x^(n^3)] theta_3(x)^n, where theta_3() is the Jacobi theta function.
a(n) = [x^(n^3)] (Sum_{k=-infinity..infinity} x^(k^2))^n.
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