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 1-5 of 5 results.

A238801 Triangle T(n,k), read by rows, given by T(n,k) = C(n+1, k+1)*(1-(k mod 2)).

Original entry on oeis.org

1, 2, 0, 3, 0, 1, 4, 0, 4, 0, 5, 0, 10, 0, 1, 6, 0, 20, 0, 6, 0, 7, 0, 35, 0, 21, 0, 1, 8, 0, 56, 0, 56, 0, 8, 0, 9, 0, 84, 0, 126, 0, 36, 0, 1, 10, 0, 120, 0, 252, 0, 120, 0, 10, 0, 11, 0, 165, 0, 462, 0, 330, 0, 55, 0, 1, 12, 0, 220, 0, 792, 0, 792, 0, 220, 0, 12, 0
Offset: 0

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Author

Philippe Deléham, Mar 05 2014

Keywords

Comments

Row sums are powers of 2.

Examples

			Triangle begins:
1;
2, 0;
3, 0, 1;
4, 0, 4, 0;
5, 0, 10, 0, 1;
6, 0, 20, 0, 6, 0;
7, 0, 35, 0, 21, 0, 1;
8, 0, 56, 0, 56, 0, 8, 0;
9, 0, 84, 0, 126, 0, 36, 0, 1;
10, 0, 120, 0, 252, 0, 120, 0, 10, 0; etc.
		

Crossrefs

Programs

  • Mathematica
    Table[Binomial[n + 1, k + 1]*(1 - Mod[k , 2]), {n, 0, 10}, {k, 0, n}] // Flatten (* G. C. Greubel, Nov 22 2017 *)
  • PARI
    T(n,k) = binomial(n+1, k+1)*(1-(k % 2));
    tabl(nn) = for (n=0, nn, for (k=0, n, print1(T(n,k), ", ")); print); \\ Michel Marcus, Nov 23 2017

Formula

G.f.: 1/((1+(y-1)*x)*(1-(y+1)*x)).
T(n,k) = 2*T(n-1,k) + T(n-2,k-2) - T(n-2,k), T(0,0) = 1, T(1,0) = 2, T(1,1) = 0, T(n,k) = 0 if k<0 or if k>n.
Sum_{k=0..n} T(n,k)*x^k = A000027(n+1), A000079(n), A015518(n+1), A003683(n+1), A079773(n+1), A051958(n+1), A080920(n+1), A053455(n), A160958(n+1) for x = 0, 1, 2, 3, 4, 5, 6, 7, 8 respectively.

A010984 Binomial coefficient C(n,31).

Original entry on oeis.org

1, 32, 528, 5984, 52360, 376992, 2324784, 12620256, 61523748, 273438880, 1121099408, 4280561376, 15338678264, 51915526432, 166871334960, 511738760544, 1503232609098, 4244421484512, 11554258485616, 30405943383200, 77535155627160, 191991813933920
Offset: 31

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Author

Keywords

Crossrefs

Programs

Formula

G.f.: x^31/(1-x)^32. - Zerinvary Lajos, Dec 19 2008; adapted to offset by Enxhell Luzhnica, Jan 21 2017
From Amiram Eldar, Dec 12 2020: (Start)
Sum_{n>=31} 1/a(n) = 31/30.
Sum_{n>=31} (-1)^(n+1)/a(n) = A001787(31)*log(2) - A242091(31)/30! = 33285996544*log(2) - 6717121856795533085173/291136195350 = 0.9704936372... (End)

A010981 Binomial coefficient C(n,28).

Original entry on oeis.org

1, 29, 435, 4495, 35960, 237336, 1344904, 6724520, 30260340, 124403620, 472733756, 1676056044, 5586853480, 17620076360, 52860229080, 151532656696, 416714805914, 1103068603890, 2818953098830, 6973199770790, 16735679449896, 39049918716424, 88749815264600
Offset: 28

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Author

Keywords

Comments

Coordination sequence for 28-dimensional cyclotomic lattice Z[zeta_29].

Crossrefs

Programs

Formula

G.f.: x^28/(1-x)^29. - Zerinvary Lajos, Aug 18 2008; adapted to offset by Enxhell Luzhnica, Jan 21 2017
From Amiram Eldar, Dec 12 2020: (Start)
Sum_{n>=28} 1/a(n) = 28/27.
Sum_{n>=28} (-1)^n/a(n) = A001787(28)*log(2) - A242091(28)/27! = 3758096384*log(2) - 1867942673688249668/717084225 = 0.9676178392... (End)

A010982 Binomial coefficient C(n,29).

Original entry on oeis.org

1, 30, 465, 4960, 40920, 278256, 1623160, 8347680, 38608020, 163011640, 635745396, 2311801440, 7898654920, 25518731280, 78378960360, 229911617056, 646626422970, 1749695026860, 4568648125690, 11541847896480, 28277527346376, 67327446062800, 156077261327400
Offset: 29

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Author

Keywords

Crossrefs

Programs

Formula

G.f.: x^29/(1-x)^30. - Zerinvary Lajos, Dec 19 2008; adapted to offset by Enxhell Luzhnica, Jan 21 2017
From Amiram Eldar, Dec 12 2020: (Start)
Sum_{n>=29} 1/a(n) = 29/28.
Sum_{n>=29} (-1)^(n+1)/a(n) = A001787(29)*log(2) - A242091(29)/28! = 7784628224*log(2) - 108340675094713923269/20078358300 = 0.9686369528... (End)

A095704 Triangle read by rows giving coefficients of the trigonometric expansion of sin(n*x).

Original entry on oeis.org

1, 2, 0, 3, 0, -1, 4, 0, -4, 0, 5, 0, -10, 0, 1, 6, 0, -20, 0, 6, 0, 7, 0, -35, 0, 21, 0, -1, 8, 0, -56, 0, 56, 0, -8, 0, 9, 0, -84, 0, 126, 0, -36, 0, 1, 10, 0, -120, 0, 252, 0, -120, 0, 10, 0, 11, 0, -165, 0, 462, 0, -330, 0, 55, 0, -1, 12, 0, -220, 0, 792, 0, -792, 0, 220, 0, -12, 0, 13, 0, -286, 0, 1287, 0
Offset: 1

Views

Author

Robert G. Wilson v, Jul 06 2004

Keywords

Examples

			The trigonometric expansion of sin(4x) is 4*cos(x)^3*sin(x) - 4*cos(x)*sin(x)^3, so the fourth row is 4, 0, -4, 0.
Triangle begins:
1
2 0
3 0 -1
4 0 -4 0
5 0 -10 0 1
6 0 -20 0 6 0
7 0 -35 0 21 0 -1
8 0 -56 0 56 0 -8 0
		

Crossrefs

First column is A000027 = C(n, 1), third column is A000292 = C(n, 3), fifth column is A000389 = C(n, 5), seventh column is A000580 = C(n, 7), ninth column is A000582 = C(n, 9).
A001288 = C(n, 11), A010966 = C(n, 13), A010968 = C(n, 15), A010970 = C(n, 17), A010972 = C(n, 19),
A010974 = C(n, 21), A010976 = C(n, 23), A010978 = C(n, 25), A010980 = C(n, 27), A010982 = C(n, 29),
A010984 = C(n, 31), A010986 = C(n, 33), A010988 = C(n, 35), A010990 = C(n, 37), A010992 = C(n, 39),
A010994 = C(n, 41), A010996 = C(n, 43), A010998 = C(n, 45), A011000 = C(n, 47), A017713 = C(n, 49)
Another version of the triangle in A034867. Cf. A096754.
A017715 = C(n, 51), A017717 = C(n, 53), A017719 = C(n, 55), A017721 = C(n, 57), etc.

Programs

  • Mathematica
    Flatten[ Table[ Plus @@ CoefficientList[ TrigExpand[ Sin[n*x]], {Sin[x], Cos[x]}], {n, 13}]]

Formula

T(n,k) = C(n+1,k+1)*sin(Pi*(k+1)/2). - Paul Barry, May 21 2006
Showing 1-5 of 5 results.