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.

A299034 a(n) = n! * [x^n] Product_{k>=1} 1/(1 - x^k)^(n/k).

Original entry on oeis.org

1, 1, 8, 93, 1544, 32615, 843264, 25739539, 906373376, 36163950849, 1612483625600, 79458277381901, 4288069172500992, 251520785449249927, 15932801526165085184, 1084003570689331039875, 78835487923639854792704, 6103175938145968656408641, 501114006272655771562911744
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 01 2018

Keywords

Examples

			The table of coefficients of x^k in expansion of e.g.f. Product_{k>=1} 1/(1 - x^k)^(n/k) begins:
n = 0: (1), 0,   0,    0,     0,      0,       0,  ...
n = 1:  1, (1),  3,   11,    59,    339,    2629,  ...
n = 2:  1,  2,  (8),  40,   260,   1928,   17056,  ...
n = 3:  1,  3,  15,  (93),  711,   6237,   62901,  ...
n = 4:  1,  4,  24,  176, (1544), 15456,  174784,  ...
n = 5:  1,  5,  35,  295,  2915, (32615), 407725,  ...
n = 6:  1,  6,  48,  456,  5004,  61704, (843264), ...
		

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[Product[1/(1 - x^k)^(n/k), {k, 1, n}], {x, 0, n}], {n, 0, 18}]

Formula

a(n) = n! * [x^n] exp(n*Sum_{k>=1} d(k)*x^k/k), where d(k) is the number of divisors of k (A000005).
a(n) ~ c * d^n * n^n, where d = 1.7257974131308983723949107467... and c = 0.693704376971941705824592525... - Vaclav Kotesovec, Sep 08 2018

A300187 a(n) = n! * [x^n] Product_{k>=1} (1 + x^k)^(n/k).

Original entry on oeis.org

1, 1, 4, 39, 488, 7615, 147024, 3371137, 89079808, 2665537713, 89142430400, 3295096700071, 133399600068096, 5870116973678191, 278971698167158528, 14239859507270510625, 776985219329347518464, 45130494178637796970273, 2780224621391401396134912, 181059775626543107582734183
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 28 2018

Keywords

Examples

			The table of coefficients of x^k in expansion of e.g.f. Product_{k>=1} (1 + x^k)^(n/k) begins:
n = 0: (1), 0,   0,    0,     0,      0,       0,  ...
n = 1:  1, (1),  1,    5,    11,     59,     439,  ...
n = 2:  1,  2,  (4),  16,    68,    328,    2416,  ...
n = 3:  1,  3,   9,  (39),  207,   1197,    8811,  ...
n = 4:  1,  4,  16,   80,  (488),  3296,   25984,  ...
n = 5:  1,  5,  25,  145,   995,  (7615),  65575,  ...
n = 6:  1,  6,  36,  240,  1836,  15624, (147024), ...
		

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[Product[(1 + x^k)^(n/k), {k, 1, n}], {x, 0, n}], {n, 0, 19}]

Formula

a(n) = n! * [x^n] exp(n*Sum_{k>=1} A048272(k)*x^k/k).
a(n) ~ c * d^n * n^n, where d = 1.294982800733109500251... and c = 0.6755467963500480915... - Vaclav Kotesovec, Sep 07 2018

A300188 a(n) = n! * [x^n] Product_{k>=1} 1/(1 + x^k)^(n/k).

Original entry on oeis.org

1, -1, 4, -39, 536, -9115, 185904, -4461877, 123647488, -3886461081, 136538590400, -5300491027711, 225313697972736, -10409021924850211, 519298241645107456, -27824560148201248125, 1593597443825288904704, -97153909607626767338353, 6281720886474120790582272
Offset: 0

Views

Author

Ilya Gutkovskiy, Feb 28 2018

Keywords

Examples

			The table of coefficients of x^k in expansion of e.g.f. Product_{k>=1} 1/(1 + x^k)^(n/k) begins:
n = 0: (1),  0,   0,     0,     0,       0,        0,  ...
n = 1:  1, (-1),  1,    -5,    23,    -119,      619,  ...
n = 2:  1,  -2,  (4),  -16,    92,    -568,     3856,  ...
n = 3:  1,  -3,   9,  (-39),  243,   -1737,    13671,  ...
n = 4:  1,  -4,  16,   -80,  (536),  -4256,    37504,  ...
n = 5:  1,  -5,  25,  -145,  1055,  (-9115),   88075,  ...
n = 6:  1,  -6,  36,  -240,  1908,  -17784,  (185904), ...
		

Crossrefs

Programs

  • Mathematica
    Table[n! SeriesCoefficient[Product[1/(1 + x^k)^(n/k), {k, 1, n}], {x, 0, n}], {n, 0, 18}]

Formula

a(n) = n! * [x^n] exp(-n*Sum_{k>=1} A048272(k)*x^k/k).
a(n) ~ (-1)^n * c * d^n * n^n, where d = 1.3587950730244927060955... and c = 0.6449711831436950784... - Vaclav Kotesovec, Sep 08 2018
Showing 1-3 of 3 results.