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.

A136431 Hyperfibonacci square number array a(k,n) = F(n)^(k), read by ascending antidiagonals (k, n >= 0).

Original entry on oeis.org

0, 0, 1, 0, 1, 1, 0, 1, 2, 2, 0, 1, 3, 4, 3, 0, 1, 4, 7, 7, 5, 0, 1, 5, 11, 14, 12, 8, 0, 1, 6, 16, 25, 26, 20, 13, 0, 1, 7, 22, 41, 51, 46, 33, 21, 0, 1, 8, 29, 63, 92, 97, 79, 54, 34, 0, 1, 9, 37, 92, 155, 189, 176, 133, 88, 55, 0, 1, 10, 46, 129, 247, 344, 365, 309, 221, 143, 89, 0, 1
Offset: 0

Views

Author

Jonathan Vos Post, Apr 01 2008

Keywords

Comments

Main diagonal is A108081. Antidiagonal sums form A027934. - Gerald McGarvey, Oct 01 2008
Seen as triangle read by rows: T(n,0) = 1, T(n,n) = A000045(n) and for 0 < k < n: T(n,k) = T(n-1,k-1) + T(n-1,k). - Reinhard Zumkeller, Jul 16 2013

Examples

			The array F(n)^(k) begins:
.....|n=0|n=1|.n=2|.n=3|.n=4.|.n=5.|..n=6.|.n=7..|..n=8..|..n=9..|.n=10..|.in.OEIS
k=0..|.0.|.1.|..1.|..2.|...3.|...5.|....8.|...13.|....21.|....34.|....55.|.A000045
k=1..|.0.|.1.|..2.|..4.|...7.|..12.|...20.|...33.|....54.|....88.|...143.|.A000071
k=2..|.0.|.1.|..3.|..7.|..14.|..26.|...46.|...79.|...133.|...221.|...364.|.A001924
k=3..|.0.|.1.|..4.|.11.|..25.|..51.|...97.|..176.|...309.|...530.|...894.|.A014162
k=4..|.0.|.1.|..5.|.16.|..41.|..92.|..189.|..365.|...674.|..1204.|..2098.|.A014166
k=5..|.0.|.1.|..6.|.22.|..63.|.155.|..344.|..709.|..1383.|..2587.|..4685.|.A053739
k=6..|.0.|.1.|..7.|.29.|..92.|.247.|..591.|.1300.|..2683.|..5270.|..9955.|.A053295
k=7..|.0.|.1.|..8.|.37.|.129.|.376.|..967.|.2267.|..4950.|.10220.|.20175.|.A053296
k=8..|.0.|.1.|..9.|.46.|.175.|.551.|.1518.|.3785.|..8735.|.18955.|.39130.|.A053308
k=9..|.0.|.1.|.10.|.56.|.231.|.782.|.2300.|.6085.|.14820.|.33775.|.72905.|.A053309
		

Crossrefs

Programs

  • Haskell
    a136431 n k = a136431_tabl !! n !! k
    a136431_row n = a136431_tabl !! n
    a136431_tabl = map fst $ iterate h ([0], 1) where
       h (row, fib) = (zipWith (+) ([0] ++ row) (row ++ [fib]), last row)
    -- Reinhard Zumkeller, Jul 16 2013
  • Maple
    A136431 := proc(k,n) local x ; coeftayl(x/(1-x-x^2)/(1-x)^k,x=0,n) ; end: for d from 0 to 20 do for n from 0 to d do printf("%d,",A136431(d-n,n)) ; od: od: # R. J. Mathar, Apr 25 2008
  • Mathematica
    t[n_, k_] := CoefficientList[Series[x/(1 - x - x^2)/(1 - x)^k, {x, 0, n + 1}], x][[n + 1]]; Table[ t[n, k - n], {k, 0, 11}, {n, 0, k}] // Flatten
    (* To view the table above *) Table[ t[n, k], {k, 0, 9}, {n, 0, 10}] // TableForm

Formula

a(k,n) = Apply partial sum operator k times to Fibonacci numbers.
For k > 0 and n > 1, a(k,n) = a(k-1,n) + a(k,n-1). - Gerald McGarvey, Oct 01 2008

A371742 a(n) = Sum_{k=0..floor(n/2)} binomial(3*n-k,n-2*k).

Original entry on oeis.org

1, 3, 16, 92, 551, 3380, 21065, 132771, 843944, 5399802, 34731776, 224361283, 1454557294, 9458829681, 61670895633, 403003997300, 2638776935215, 17308508054848, 113709379928689, 748069400432262, 4927608724973776, 32495826854732633, 214521754579553129
Offset: 0

Views

Author

Seiichi Manyama, Apr 05 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\2, binomial(3*n-k, n-2*k));

Formula

a(n) = [x^n] 1/((1-x-x^2) * (1-x)^(2*n)).
a(n) ~ 3^(3*n + 3/2) / (5 * sqrt(Pi*n) * 2^(2*n)). - Vaclav Kotesovec, Apr 05 2024

A159965 Riordan array (1/sqrt(1-4x), (1-2x-(1-3x)c(x))/(x*sqrt(1-4x))), c(x) the g.f. of A000108.

Original entry on oeis.org

1, 2, 1, 6, 5, 1, 20, 21, 8, 1, 70, 84, 45, 11, 1, 252, 330, 220, 78, 14, 1, 924, 1287, 1001, 455, 120, 17, 1, 3432, 5005, 4368, 2380, 816, 171, 20, 1, 12870, 19448, 18564, 11628, 4845, 1330, 231, 23, 1, 48620, 75582, 77520, 54264, 26334, 8855, 2024, 300, 26, 1
Offset: 0

Views

Author

Paul Barry, Apr 28 2009

Keywords

Comments

Product of A007318 and A114422. Product of A007318^2 and A116382. Row sums are A108080.
Diagonal sums are A108081.
Riordan array (1/sqrt(1 - 4*x), x*c(x)^3) obtained from A092392 by taking every third column starting from column 0; x*c(x)^3 is the o.g.f. for A000245. - Peter Bala, Nov 24 2015

Examples

			Triangle begins
1,
2, 1,
6, 5, 1,
20, 21, 8, 1,
70, 84, 45, 11, 1,
252, 330, 220, 78, 14, 1,
924, 1287, 1001, 455, 120, 17, 1,
3432, 5005, 4368, 2380, 816, 171, 20, 1
		

Crossrefs

Programs

  • Magma
    /* As triangle */ [[Binomial(2*n+k, n+2*k): k in [0..n]]: n in [0.. 15]]; // Vincenzo Librandi, Nov 27 2015

Formula

Number triangle T(n,k) = Sum_{j = 0..n} binomial(n+k,j-k)*binomialC(n,j).
T(n,k) = binomial(2*n + k, n + 2*k). - Peter Bala, Nov 24 2015

A371743 a(n) = Sum_{k=0..floor(n/2)} binomial(4*n-k,n-2*k).

Original entry on oeis.org

1, 4, 29, 231, 1926, 16491, 143683, 1267395, 11282393, 101151544, 912011633, 8260998772, 75115815749, 685232639419, 6268299350776, 57478389714473, 528167137069958, 4862304525663579, 44836026545219765, 414048025058547788, 3828677665694353049
Offset: 0

Views

Author

Seiichi Manyama, Apr 05 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\2, binomial(4*n-k, n-2*k));

Formula

a(n) = [x^n] 1/((1-x-x^2) * (1-x)^(3*n)).
a(n) ~ 2^(8*n + 5/2) / (11 * sqrt(Pi*n) * 3^(3*n - 1/2)). - Vaclav Kotesovec, Apr 05 2024

A371744 a(n) = Sum_{k=0..floor(n/2)} binomial(5*n-k,n-2*k).

Original entry on oeis.org

1, 5, 46, 469, 5017, 55177, 617905, 7008264, 80241790, 925457822, 10735707149, 125128265025, 1464140655619, 17188834766497, 202366206841241, 2388313959181973, 28246993739096305, 334711010978735163, 3972765235517468758, 47224110710958716845
Offset: 0

Views

Author

Seiichi Manyama, Apr 05 2024

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\2, binomial(5*n-k, n-2*k));

Formula

a(n) = [x^n] 1/((1-x-x^2) * (1-x)^(4*n)).
a(n) ~ 5^(5*n + 3/2) / (19 * sqrt(Pi*n) * 2^(8*n - 1/2)). - Vaclav Kotesovec, Apr 05 2024

A133915 a(n) = Sum_{i=0..n} C(2*n-i,n+i)*2^i.

Original entry on oeis.org

1, 2, 8, 30, 116, 452, 1772, 6974, 27524, 108852, 431168, 1709996, 6788536, 26971856, 107235668, 426594110, 1697855876, 6760326116, 26927208368, 107288242820, 427596003416, 1704598377176, 6796820059928, 27106584400460, 108123625907816, 431355955330952
Offset: 0

Views

Author

Paul Barry, Sep 28 2007

Keywords

Comments

A transform of the Jacobsthal numbers A001045(n+1) under the mapping g(x)->(1/(c(x)*sqrt(1-4*x)))*g(x*c(x)), c(x) the g.f. of A000108. Hankel transform is A001787(n+1).

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[(1-4*x+(1-x)*Sqrt[1-4*x])/((x+2)*(1-4*x)^(3/2)), {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 20 2012 *)
  • PARI
    a(n) = sum(i=0, n, binomial(2*n-i, n+i)*2^i); \\ Michel Marcus, Jul 08 2021

Formula

G.f.: (1-4*x+(1-x)*sqrt(1-4*x))/((x+2)*(1-4*x)^(3/2)).
a(n) = Sum_{k=0..n} C(2*n-k,n+k)*2^k.
a(n) = Sum_{k=0..n} C(n+k-1,k)*A001045(n-k+1).
2*n*a(n) +3*(4-5*n)*a(n-1) +6*(4*n-7)*a(n-2) + 8*(2*n-3)*a(n-3)=0. - R. J. Mathar, Nov 14 2011
a(n) ~ 4^n/3. - Vaclav Kotesovec, Oct 20 2012

A360149 a(n) = Sum_{k=0..floor(n/2)} binomial(2*n+k,n-2*k).

Original entry on oeis.org

1, 2, 7, 27, 107, 429, 1731, 7012, 28478, 115864, 471991, 1924483, 7852083, 32053208, 130893949, 534673600, 2184482707, 8926392419, 36479840422, 149095843951, 609400587426, 2490900041118, 10181669553847, 41618414303969, 170118507902985, 695366323719302
Offset: 0

Views

Author

Seiichi Manyama, Jan 28 2023

Keywords

Crossrefs

Programs

  • Maple
    A360149 := proc(n)
        add(binomial(2*n+k,n-2*k),k=0..floor(n/2)) ;
    end proc:
    seq(A360149(n),n=0..40) ; # R. J. Mathar, Mar 02 2023
  • Mathematica
    a[n_] := Sum[Binomial[2*n + k, n - 2*k], {k, 0, Floor[n/2]}]; Array[a, 26, 0] (* Amiram Eldar, Jan 28 2023 *)
  • PARI
    a(n) = sum(k=0, n\2, binomial(2*n+k, n-2*k));
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(1/(sqrt(1-4*x)*(1-x^2*(2/(1+sqrt(1-4*x)))^5)))

Formula

G.f.: 1 / ( sqrt(1-4*x) * (1 - x^2 * c(x)^5) ), where c(x) is the g.f. of A000108.
a(n) ~ sqrt((7 - 5*(2/(173 + 21*sqrt(69)))^(1/3) + ((173 + 21*sqrt(69))/2)^(1/3)) / 69) / ((4 - (2/(25 - 3*sqrt(69)))^(1/3) - ((25 - 3*sqrt(69))/2)^(1/3))/3)^n. - Vaclav Kotesovec, Jan 28 2023
D-finite with recurrence n*(47*n-1011)*a(n) +(-261*n^2 +8567*n -6378)*a(n-1) +2*(-165*n^2 -9388*n +16143)*a(n-2) +(3089*n^2 +919*n -27492)*a(n-3) +2*(-1283*n^2 +3900*n +3981)*a(n-4) +4*(81*n+11)*(2*n-9)*a(n-5)=0. - R. J. Mathar, Mar 02 2023
Showing 1-7 of 7 results.