A294845 -id:A294845 - cp's OEIS frontend

A294842 Expansion of Product_{k>=1} (1 + x^k)^(k^2*(k+1)/2).

1, 1, 6, 24, 73, 238, 722, 2175, 6343, 18177, 50982, 140671, 382227, 1023623, 2706184, 7067324, 18250671, 46635309, 117997008, 295794098, 735030985, 1811435607, 4429226677, 10749552338, 25903858181, 62000039513, 147435739522, 348431110651, 818549931526, 1912010876019, 4441687009798

Offset: 0

Ilya Gutkovskiy, Nov 09 2017

nonn

Weigh transform of the pentagonal pyramidal numbers (A002411).

Vaclav Kotesovec, Table of n, a(n) for n = 0..2000
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to arXiv version]
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
N. J. A. Sloane, Transforms
Eric Weisstein's World of Mathematics, Pentagonal Pyramidal Number

Cf. A002411, A258343, A281156, A294102, A294839, A294843, A294844, A294845.

nmax = 30; CoefficientList[Series[Product[(1 + x^k)^(k^2 (k + 1)/2), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, Sum[Sum[(-1)^(k/d + 1) d^3 (d + 1)/2, {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 30}]

G.f.: Product_{k>=1} (1 + x^k)^A002411(k).

a(n) ~ exp(-2401 * Pi^16 / (2^12 * 3^11 * 5^8 * Zeta(5)^3) + (343 * Pi^12 / (2^(38/5) * 3^(37/5) * 5^(36/5) * Zeta(5)^(11/5))) * n^(1/5) - (49*Pi^8 / (2^(31/5) * 3^(24/5) * 5^(22/5) * Zeta(5)^(7/5))) * n^(2/5) + (7*Pi^4 / (2^(14/5) * 3^(16/5) * 5^(8/5) * Zeta(5)^(3/5))) * n^(3/5) + (5 * 3^(2/5) * (5*Zeta(5))^(1/5) / 2^(12/5)) * n^(4/5)) * 3^(1/5) * Zeta(5)^(1/10) / (2^(167/240) * 5^(2/5) * sqrt(Pi) * n^(3/5)). - Vaclav Kotesovec, Nov 10 2017

A294843 Expansion of Product_{k>=1} (1 + x^k)^(k(k+1)(4*k-1)/6).

Original entry on oeis.org

1, 1, 7, 29, 93, 320, 1026, 3256, 9995, 30102, 88722, 257042, 732876, 2058370, 5703858, 15606076, 42203027, 112882223, 298849221, 783574536, 2035876825, 5244191462, 13398463986, 33967008194, 85476285603, 213583335753, 530099612487, 1307195997381, 3203555001240, 7804386224233

Offset: 0

Ilya Gutkovskiy, Nov 09 2017

nonn

Weigh transform of the hexagonal pyramidal numbers (A002412).

M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to arXiv version]
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
N. J. A. Sloane, Transforms
Eric Weisstein's World of Mathematics, Hexagonal Pyramidal Number

Cf. A002412, A028377, A258343, A281156, A294836, A294842, A294844, A294845.

nmax = 29; CoefficientList[Series[Product[(1 + x^k)^(k (k + 1)(4 k - 1)/6), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, Sum[Sum[(-1)^(k/d + 1) d^2 (d + 1)(4 d - 1)/6, {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 29}]

G.f.: Product_{k>=1} (1 + x^k)^A002412(k).

a(n) ~ exp(-2401 * Pi^16 / (671846400000000 * Zeta(5)^3) - 49*Pi^8 * Zeta(3) / (518400000 * Zeta(5)^2) - Zeta(3)^2 / (2400*Zeta(5)) + (343 * Pi^12 / (77760000000 * 15^(1/5) * Zeta(5)^(11/5)) + 7*Pi^4*Zeta(3) / (72000 * 15^(1/5) * Zeta(5)^(6/5))) * n^(1/5) - (49*Pi^8 / (8640000 * 15^(2/5) * Zeta(5)^(7/5)) + Zeta(3) / (8 * (15*Zeta(5))^(2/5))) * n^(2/5) + (7*Pi^4 / (720 * (15*Zeta(5))^(3/5))) * n^(3/5) + (5*(15*Zeta(5))^(1/5)/4) * n^(4/5)) * (3*Zeta(5))^(1/10) / (2^(173/360) * 5^(2/5) * sqrt(Pi) * n^(3/5)). - Vaclav Kotesovec, Nov 10 2017

A294844 Expansion of Product_{k>=1} (1 + x^k)^(k(k+1)(5*k-2)/6).

Original entry on oeis.org

1, 1, 8, 34, 114, 411, 1380, 4573, 14650, 45995, 141296, 426364, 1265443, 3698011, 10657134, 30312395, 85183177, 236681860, 650686538, 1771098691, 4775571943, 12762628737, 33821018537, 88909273699, 231945942992, 600700301298, 1544897610261, 3946762859175, 10018454809275, 25274880698255

Offset: 0

Ilya Gutkovskiy, Nov 09 2017

nonn

Weigh transform of the heptagonal pyramidal numbers (A002413).

M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to arXiv version]
M. Bernstein and N. J. A. Sloane, Some canonical sequences of integers, Linear Alg. Applications, 226-228 (1995), 57-72; erratum 320 (2000), 210. [Link to Lin. Alg. Applic. version together with omitted figures]
N. J. A. Sloane, Transforms
Eric Weisstein's World of Mathematics, Heptagonal Pyramidal Number

Cf. A002413, A258343, A281156, A294837, A294840, A294842, A294843, A294845.

nmax = 29; CoefficientList[Series[Product[(1 + x^k)^(k (k + 1) (5 k - 2)/6), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, Sum[Sum[(-1)^(k/d + 1) d^2 (d + 1) (5 d - 2)/6, {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 29}]

G.f.: Product_{k>=1} (1 + x^k)^A002413(k).

a(n) ~ (3*Zeta(5))^(1/10) / (2^(479/720) * 5^(3/10) * sqrt(Pi) * n^(3/5)) * exp(-2401 * Pi^16 / (1312200000000000 * Zeta(5)^3) - 49 * Pi^8 * Zeta(3) / (405000000 * Zeta(5)^2) - Zeta(3)^2 / (750*Zeta(5)) + (343*Pi^12 / (60750000000 * 2^(3/5) * 3^(1/5) * 5^(2/5) * Zeta(5)^(11/5)) + 7*Pi^4 * Zeta(3) / (22500 * 2^(3/5) * 3^(1/5) * 5^(2/5) * Zeta(5)^(6/5))) * n^(1/5) - (49*Pi^8 / (5400000 * 2^(1/5) * 3^(2/5) * 5^(4/5) * Zeta(5)^(7/5)) + Zeta(3) / (2^(6/5) * 5^(4/5) * (3*Zeta(5))^(2/5))) * n^(2/5) + (7*Pi^4 / (900 * 2^(4/5) * 5^(1/5) * (3*Zeta(5))^(3/5))) * n^(3/5) + (5^(7/5) * (3*Zeta(5))^(1/5) / 2^(12/5)) * n^(4/5)). - Vaclav Kotesovec, Nov 10 2017

A318125 a(n) = [x^n] exp(Sum_{k>=1} (-1)^(k+1)x^k(1 + (n - 3)x^k)/(k(1 - x^k)^4)).

Original entry on oeis.org

1, 1, 3, 14, 54, 238, 1026, 4573, 20404, 91902, 415953, 1891908, 8638846, 39569655, 181766878, 836950153, 3861927937, 17853107055, 82668539290, 383360628369, 1780126898575, 8275908734103, 38517137597486, 179442212204245, 836741558761935, 3905012142470483

Offset: 0

Ilya Gutkovskiy, Aug 18 2018

nonn

For n > 2, a(n) is the n-th term of the weigh transform of n-gonal pyramidal numbers.

N. J. A. Sloane, Transforms
Index to sequences related to pyramidal numbers

Cf. A258343, A281156, A294842, A294843, A294844, A294845, A318121, A318124.

Table[SeriesCoefficient[Exp[Sum[(-1)^(k + 1) x^k (1 + (n - 3) x^k)/(k (1 - x^k)^4), {k, 1, n}]], {x, 0, n}], {n, 0, 25}]

a(n) ~ c * d^n / sqrt(n), where d = 4.761510955746025663058811... and c = 0.2241869836397882024713... - Vaclav Kotesovec, Aug 19 2018

cp's OEIS Frontend

A294842 Expansion of Product_{k>=1} (1 + x^k)^(k^2*(k+1)/2).

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A294843 Expansion of Product_{k>=1} (1 + x^k)^(k*(k+1)*(4*k-1)/6).

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A294844 Expansion of Product_{k>=1} (1 + x^k)^(k*(k+1)*(5*k-2)/6).

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A318125 a(n) = [x^n] exp(Sum_{k>=1} (-1)^(k+1)*x^k*(1 + (n - 3)*x^k)/(k*(1 - x^k)^4)).

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A294843 Expansion of Product_{k>=1} (1 + x^k)^(k(k+1)(4*k-1)/6).

A294844 Expansion of Product_{k>=1} (1 + x^k)^(k(k+1)(5*k-2)/6).

A318125 a(n) = [x^n] exp(Sum_{k>=1} (-1)^(k+1)x^k(1 + (n - 3)x^k)/(k(1 - x^k)^4)).