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 1-3 of 3 results.

A300520 Expansion of Product_{k>=1} 1 / (1 - Fibonacci(k)*x^k).

Original entry on oeis.org

1, 1, 2, 4, 8, 15, 31, 57, 113, 212, 410, 757, 1464, 2684, 5083, 9380, 17569, 32120, 59977, 109193, 202046, 367951, 675541, 1224453, 2243795, 4052369, 7377243, 13314989, 24140198, 43406515, 78510429, 140800279, 253663615, 454352111, 815790813, 1457485309
Offset: 0

Views

Author

Vaclav Kotesovec, Mar 08 2018

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 40; CoefficientList[Series[Product[1/(1-Fibonacci[k]*x^k), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

log(a(n)) ~ log(phi)*n + 2*sqrt(polylog(2, 1/sqrt(5))*n) - 3*(log(n)/4), where polylog(2, 1/sqrt(5)) = 0.5107013915606224266804289751265205446721... and phi = A001622 = (1 + sqrt(5))/2 is the golden ratio.

A318264 Expansion of Product_{k>=1} (1 + C(k)*x^k), where C(k) is the Catalan number A000108.

Original entry on oeis.org

1, 1, 2, 7, 19, 66, 212, 743, 2487, 9012, 31177, 113775, 404584, 1490726, 5376676, 20028981, 73068861, 273659672, 1009921813, 3801386137, 14125670266, 53477758556, 199950414035, 759566205693, 2857261603610, 10889590477287, 41136917417501, 157329747348492
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 22 2018

Keywords

Crossrefs

Programs

  • Maple
    C:= proc(n) option remember; binomial(n+n, n)/(n+1) end:
    b:= proc(n, i) option remember; `if`(i*(i+1)/2 b(n$2):
    seq(a(n), n=0..30);  # Alois P. Heinz, Aug 23 2019
  • Mathematica
    nmax = 40; CoefficientList[Series[Product[1+CatalanNumber[k]*x^k, {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 40; poly = ConstantArray[0, nmax + 1]; poly[[1]] = 1; poly[[2]] = 1; Do[Do[poly[[j + 1]] += CatalanNumber[k]*poly[[j - k + 1]], {j, nmax, k, -1}];, {k, 2, nmax}]; poly

Formula

a(n) ~ c * A000108(n) ~ c * 4^n / (sqrt(Pi) * n^(3/2)), where c = Product_{k>=1} (1 + C(k)/4^k) = 2.608465265690846547082817204714986077801494... - Vaclav Kotesovec, Aug 24 2018

A318263 Expansion of Product_{k>=1} (1 + Lucas(k)*x^k).

Original entry on oeis.org

1, 1, 3, 7, 11, 30, 62, 129, 235, 541, 1034, 2101, 4140, 8129, 15984, 31903, 60398, 117646, 228808, 433768, 836552, 1601282, 3031299, 5736396, 10899112, 20466182, 38556342, 72522116, 135662847, 253047629, 473785878, 878655661, 1634304062, 3033385668, 5608183925
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 22 2018

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 40; CoefficientList[Series[Product[1+LucasL[k]*x^k, {k, 1, nmax}], {x, 0, nmax}], x]
    nmax = 40; poly = ConstantArray[0, nmax + 1]; poly[[1]] = 1; poly[[2]] = 1; Do[Do[poly[[j + 1]] += LucasL[k]*poly[[j - k + 1]], {j, nmax, k, -1}];, {k, 2, nmax}]; poly

Formula

From Vaclav Kotesovec, Aug 24 2018: (Start)
a(n) ~ c * A000032(n) * A000009(n) ~ c * phi^n * exp(Pi*sqrt(n/3)) / (4 * 3^(1/4) * n^(3/4)), where c = Product_{k>=1} ((1 + Lucas(k)/phi^k)/2) = 0.8503149035690839100210269103058319341315494385103929947491... and phi = A001622 = (1+sqrt(5))/2 is the golden ratio.
Equivalently, c = Product_{k>=1} (1 + (-1)^k/(2*phi^(2*k))),
c = 2/3 * QPochhammer[-1/2, -1/GoldenRatio^2]. (End)
Showing 1-3 of 3 results.