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 1-7 of 7 results.

A090317 Row sums of triangle in A090285.

Original entry on oeis.org

1, 2, 7, 28, 118, 510, 2235, 9876, 43870, 195556, 873814, 3911168, 17527904, 78622982, 352911939, 1584927828, 7120769526, 32002212252, 143859840114, 646819996008, 2908670252676, 13081556909292, 58839348572574, 264674150692488, 1190649451348908, 5356483791828840, 24098774900561500
Offset: 0

Views

Author

Philippe Deléham, Jan 25 2004

Keywords

Comments

Apply the inverse of the Riordan array (1/(1-x^2),x/(1+x)^2) to 2^n. - Paul Barry, Mar 13 2009
Hankel transform is A079935. - Paul Barry, Mar 13 2009

Crossrefs

Programs

  • Mathematica
    Table[SeriesCoefficient[(1-x^2*((1-Sqrt[1-4*x])/(2*x))^4)/(1-2*x*((1-Sqrt[1-4*x])/(2*x))^2),{x,0,n}],{n,0,20}] (* Vaclav Kotesovec, Oct 14 2012 *)
  • Maxima
    a(n):=if n=0 then 1 else 4*binomial(2*n-1,n)/(n+1)+3*sum(((k+1)*2^(k)*binomial(2*n-1,n-k-1))/(n+k+1),k,1,n-1); /* Vladimir Kruchinin, Feb 21 2019 */
  • PARI
    x='x+O('x^66); Vec((1-x^2*((1-sqrt(1-4*x))/(2*x))^4)/(1-2*x*((1-sqrt(1-4*x))/(2*x))^2)) \\ Joerg Arndt, May 11 2013
    

Formula

a(n+1) = A000108(n+1) + Sum_{k=0..n} a(n-k)*A001700(k); a(0) = 1.
G.f.: (1-x^2*c(x)^4)/(1-2x*c(x)^2), where c(x) is the g.f. of the Catalan numbers A000108. - Paul Barry, Mar 13 2009
Recurrence: 2*(n+1)*(n+3)*a(n) = (17*n^2+56*n-21)*a(n-1) - 18*(n+4)*(2*n-3)*a(n-2). - Vaclav Kotesovec, Oct 14 2012
a(n) ~ 9^n/2^(n+2). - Vaclav Kotesovec, Oct 14 2012
a(n) = 4*C(2*n-1,n)/(n+1)+3*Sum_{k=1..n-1}(k+1)*2^k*C(2*n-1,n-k-1)/(n+k+1), n>0, a(0)=1. - Vladimir Kruchinin, Feb 21 2019

Extensions

Term 15 corrected by Paul Barry, Mar 13 2009

A090294 a(n) = K_3(n) = Sum_{k>=0} A090285(3,k)*2^k*binomial(n,k). a(n) = (4*n^3+30*n^2+56*n+15)/3.

Original entry on oeis.org

5, 35, 93, 187, 325, 515, 765, 1083, 1477, 1955, 2525, 3195, 3973, 4867, 5885, 7035, 8325, 9763, 11357, 13115, 15045, 17155, 19453, 21947, 24645, 27555, 30685, 34043, 37637, 41475, 45565, 49915, 54533, 59427, 64605, 70075, 75845, 81923, 88317
Offset: 0

Views

Author

Philippe Deléham, Jan 25 2004

Keywords

Comments

Values of polynomial K_3 related to A090285.

Crossrefs

Cf. A090285.

Programs

Formula

O.g.f.: 8/(-1+x)^4+5/(-1+x)-2/(-1+x)^2-4/(-1+x)^3 . - R. J. Mathar, Feb 26 2008

A090297 a(n) = K_5(n) = Sum_{k>=0} A090285(5,k)*2^k*binomial(n,k). a(n) = 2*(2*n^5+45*n^4+360*n^3+1215*n^2+1528*n+315)/15.

Original entry on oeis.org

42, 462, 1586, 3958, 8330, 15694, 27314, 44758, 69930, 105102, 152946, 216566, 299530, 405902, 540274, 707798, 914218, 1165902, 1469874, 1833846, 2266250, 2776270, 3373874, 4069846, 4875818, 5804302, 6868722, 8083446, 9463818
Offset: 0

Views

Author

Philippe Deléham, Jan 25 2004

Keywords

Comments

Values of polynomial K_5 related to A090285.

Crossrefs

Cf. A090285.

Programs

  • Magma
    [2*(2*n^5 + 45*n^4 + 360*n^3 + 1215*n^2 + 1528*n + 315)/15: n in [0..30]]; // Vincenzo Librandi, Sep 18 2012
  • Mathematica
    Table[(2*(2*n^5 + 45*n^4 + 360*n^3 + 1215*n^2 + 1528*n + 315)/15),{n, 0, 50}] (* Vincenzo Librandi, Sep 18 2012  *)
    LinearRecurrence[{6,-15,20,-15,6,-1},{42,462,1586,3958,8330,15694},30] (* Harvey P. Dale, Apr 17 2020 *)

Formula

G.f.: (42+210*x-556*x^2+532*x^3-238*x^4+42*x^5)/(1-x)^6. [Colin Barker, Sep 18 2012]

Extensions

Corrected by T. D. Noe, Nov 09 2006

A090296 a(n) = K_4(n) = Sum_{k>=0} A090285(4,k)*2^k*binomial(n,k). a(n) = 2*(n^4+14*n^3+62*n^2+91*n+21)/3.

Original entry on oeis.org

14, 126, 386, 874, 1686, 2934, 4746, 7266, 10654, 15086, 20754, 27866, 36646, 47334, 60186, 75474, 93486, 114526, 138914, 166986, 199094, 235606, 276906, 323394, 375486, 433614, 498226, 569786, 648774, 735686, 831034, 935346, 1049166
Offset: 0

Views

Author

Philippe Deléham, Jan 25 2004

Keywords

Comments

Values of polynomial K_4 related to A090285.

Crossrefs

Cf. A090285.

A090299 Table T(n,k), n>=0 and k>=0, read by antidiagonals : the k-th column given by the k-th polynomial K_k related to A090285.

Original entry on oeis.org

1, 1, 1, 2, 3, 1, 5, 10, 5, 1, 14, 35, 22, 7, 1, 42, 126, 93, 38, 9, 1, 132, 462, 386, 187, 58, 11, 1, 429, 1716, 1586, 874, 325, 82, 13, 1, 1430, 6435, 6476, 3958, 1686, 515, 110, 15, 1, 4862, 24310, 26333, 17548, 8330, 2934, 765, 142, 17, 1
Offset: 0

Views

Author

Philippe Deléham, Jan 25 2004

Keywords

Comments

Read as a number triangle, this is the Riordan array (c(x),x/sqrt(1-4x)) where c(x) is the g.f. of A000108. - Paul Barry, May 16 2005

Examples

			row n=0 : 1, 1, 2, 5, 14, 42, 132, 429, ... see A000108.
row n=1 : 1, 3, 10, 35, 126, 462, 1716, 6435, ... see A001700.
row n=2 : 1, 5, 22, 93, 386, 1586, 6476, ... see A000346.
row n=3 : 1, 7, 38, 187, 874, 3958, 17548, ... see A000531.
row n=4 : 1, 9, 58, 325, 1686, 8330, 39796, ... see A018218.
		

Crossrefs

Other rows : A029887, A042941, A045724, A042985, A045492. Columns : A000012, A005408. Row n is the convolution of the row (n-j) with A000984, A000302, A002457, A002697 (first term omitted), A002802, A038845, A020918, A038846, A020920 for j=1, 2, ..9 respectively.

Formula

T(n, k) = K_k(n)= Sum_{j>=0} A090285(k, j)*2^j*binomial(n, j). T(n, 1) = 2*n+1. T(n, 2) = 2*A028387(n).

Extensions

Corrected by Alford Arnold, Oct 18 2006

A090288 a(n) = 2*n^2 + 6*n + 2.

Original entry on oeis.org

2, 10, 22, 38, 58, 82, 110, 142, 178, 218, 262, 310, 362, 418, 478, 542, 610, 682, 758, 838, 922, 1010, 1102, 1198, 1298, 1402, 1510, 1622, 1738, 1858, 1982, 2110, 2242, 2378, 2518, 2662, 2810, 2962, 3118, 3278, 3442, 3610, 3782, 3958, 4138, 4322, 4510
Offset: 0

Views

Author

Philippe Deléham, Jan 25 2004

Keywords

Comments

Values of polynomial K_2 related to A090285: a(n) = K_2(n) = Sum_{k>=0} A090285(2,k)*2^k*binomial(n,k).
Numbers k such that 2*k+5 is a square. - Vincenzo Librandi, Oct 10 2013
a(n) is the area of a triangle with vertices at (b(n-2),b(n-1)), (b(n),b(n+1)), and (b(n+2),B(n+3)) for b(k)=A000292(k) with n>1. - J. M. Bergot, Mar 23 2017

Crossrefs

Programs

Formula

a(n) = 2*A028387(n).
G.f.: 2*(1 +2*x -x^2)/(1-x)^3. - R. J. Mathar, Apr 02 2008
E.g.f.: 2*(1 +4*x +x^2)*exp(x). - G. C. Greubel, Jul 13 2017
Sum_{n>=0} 1/a(n) = 1/2 + Pi*tan(sqrt(5)*Pi/2)/(2*sqrt(5)). - Amiram Eldar, Dec 23 2022

Extensions

Corrected by T. D. Noe, Nov 12 2006

A236471 Riordan array ((1-x)/(1-2*x), x(1-x)/(1-2*x)^2).

Original entry on oeis.org

1, 1, 1, 2, 4, 1, 4, 13, 7, 1, 8, 38, 33, 10, 1, 16, 104, 129, 62, 13, 1, 32, 272, 450, 304, 100, 16, 1, 64, 688, 1452, 1289, 590, 147, 19, 1, 128, 1696, 4424, 4942, 2945, 1014, 203, 22, 1, 256, 4096, 12896, 17584, 13073, 5823, 1603, 268, 25, 1, 512, 9728
Offset: 0

Views

Author

Philippe Deléham, Jan 26 2014

Keywords

Comments

Row sums are A052936(n).
Diagonal sums are A121449(n).
The triangle T'(n,k) = T(n,k)*(-1)^(n+k) is the inverse of the Riordan array in A090285.

Examples

			Triangle begins:
1;
1, 1;
2, 4, 1;
4, 13, 7, 1;
8, 38, 33, 10, 1;
16, 104, 129, 62, 13, 1;
32, 272, 450, 304, 100, 16, 1;
64, 688, 1452, 1289, 590, 147, 19, 1;
		

Crossrefs

Programs

  • Mathematica
    CoefficientList[CoefficientList[Series[(2*x^2-3*x+1)/((x^2-x)*y +4*x^2 - 4*x+1), {x,0,20}, {y,0,20}], x], y]//Flatten (* G. C. Greubel, Apr 19 2018 *)
  • Maxima
    T(n,k):=sum(binomial(m+k,2*k)*binomial(n-1,n-m),m,0,n); /* Vladimir Kruchinin, Apr 21 2015 */
    
  • PARI
    for(n=0,20, for(k=0,n, print1(sum(m=0, n, binomial(m+k,2*k)* binomial(n-1,n-m)), ", "))) \\ G. C. Greubel, Apr 19 2018

Formula

T(n,0) = A011782(n), T(n,1) = A049611(n), T(n,n) = A000012(n) = 1, T(n+1,n) = A016777(n), T(n+2,n) = A062708(n+1).
G.f.: (2*x^2-3*x+1)/((x^2-x)*y+4*x^2-4*x+1). - Vladimir Kruchinin, Apr 21 2015
T(n,k) = Sum_{m=0..n} C(m+k,2*k)*C(n-1,n-m). - Vladimir Kruchinin, Apr 21 2015
Showing 1-7 of 7 results.