A307462
Expansion of Product_{k>=1} (1+x^k)^((-1)^k*k^2).
Original entry on oeis.org
1, -1, 5, -14, 36, -97, 246, -593, 1423, -3351, 7699, -17432, 38901, -85545, 185862, -399220, 848080, -1783682, 3716584, -7675916, 15722127, -31951330, 64452707, -129102947, 256876062, -507854808, 997954125, -1949631802, 3787674152, -7319306458, 14071371173
Offset: 0
Product_{k>=1} (1+x^k)^((-1)^k*k^b):
A083365 (b=0),
A284474 (b=1), this sequence (b=2).
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nmax = 40; CoefficientList[Series[Product[(1 + x^k)^((-1)^k*k^2), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Apr 09 2019 *)
nmax = 40; CoefficientList[Series[Product[(1 + x^(2*k))^(4*k^2) / (1 + x^(2*k - 1))^((2*k - 1)^2), {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Apr 09 2019 *)
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N=66; x='x+O('x^N); Vec(prod(k=1, N, (1+x^k)^((-1)^k*k^2)))
A322199
Expansion of Product_{k>=1} 1/(1 - (2^k + 1) * x^k).
Original entry on oeis.org
1, 3, 14, 51, 195, 663, 2345, 7707, 25744, 82980, 267812, 846150, 2676163, 8337189, 25947281, 80053128, 246468551, 754366239, 2305139065, 7014997404, 21317567297, 64606020012, 195557995054, 590855420007, 1783577678925, 5377112705874, 16199746640340, 48763788775530, 146712079122114, 441146762285301, 1326002750336702, 3984148679940612, 11967872331787643
Offset: 0
G.f.: A(x) = 1 + 3*x + 14*x^2 + 51*x^3 + 195*x^4 + 663*x^5 + 2345*x^6 + 7707*x^7 + 25744*x^8 + 82980*x^9 + 267812*x^10 + 846150*x^11 + 2676163*x^12 + ...
such that
A(x) = 1/( (1 - 3*x) * (1 - 5*x^2) * (1 - 9*x^3) * (1 - 17*x^4) * (1 - 33*x^5) * (1 - 65*x^6) * (1 - 129*x^7) * ... * (1 - (2^n+1)*x^n) * ... ).
RELATED SERIES.
log( A(x) ) = 3*x + 19*x^2/2 + 54*x^3/3 + 199*x^4/4 + 408*x^5/5 + 1612*x^6/6 + 3090*x^7/7 + 11023*x^8/8 + 26487*x^9/9 + 80994*x^10/10 + 199686*x^11/11 + 676540*x^12/12 + ... + A322209(n)*x^n/n + ...
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{a(n) = polcoeff( 1/prod(m=1,n, 1 - (2^m+1)*x^m +x*O(x^n)),n)}
for(n=0,30, print1(a(n),", "))
A294757
Expansion of Product_{k>=1} 1/(1 - k^k*x^k)^(k^k).
Original entry on oeis.org
1, 1, 17, 746, 66442, 9843731, 2187951485, 680615166718, 282199710311343, 150389915850565698, 100155578811552469018, 81505577529171038120173, 79580089696277797740768316, 91814299717377746850767747558
Offset: 0
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N=20; x='x+O('x^N); Vec(1/prod(k=1, N, (1-k^k*x^k)^k^k))
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sd(n) = sumdiv(n, d, d^(d+n+1));
a(n) = if (n==0, 1, sum(k=1, n, sd(k)*a(n-k))/n); \\ Michel Marcus, Nov 10 2017
A294813
Expansion of Product_{k>=1} 1/(1 - k^k*x^k)^k.
Original entry on oeis.org
1, 1, 9, 90, 1162, 17435, 310193, 6286826, 144750451, 3717959194, 105725550762, 3293914191401, 111659484775650, 4089936343858976, 160992739588472076, 6776415674628574634, 303714862444753023205, 14439925495117621425535
Offset: 0
A294953
Expansion of Product_{k>=1} (1 - k^(2*k)*x^k)^k.
Original entry on oeis.org
1, -1, -32, -2155, -259701, -48496253, -13001952944, -4732375549802, -2246504006429898, -1348407213767476321, -998562531571744073815, -894380298523142455736017, -953030939828900988652689704, -1191547999931410291515116161158
Offset: 0
A294954
Expansion of Product_{k>=1} 1/(1 - k^(2*k)*x^k)^k.
Original entry on oeis.org
1, 1, 33, 2220, 265132, 49163241, 13121450895, 4762820449382, 2257130616816421, 1353302193751862072, 1001440612663683369940, 896481723303781965832069, 954894526385647926192875010, 1193519555165192704579377833814
Offset: 0
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nmax = 20; CoefficientList[Series[Product[1/(1 - k^(2*k)*x^k)^k, {k, 1, nmax}], {x, 0, nmax}], x] (* Vaclav Kotesovec, Nov 15 2017 *)
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N=20; x='x+O('x^N); Vec(1/prod(k=1, N, (1-k^(2*k)*x^k)^k))
A295086
Expansion of Product_{k>=1} 1/(1 + x^k)^(k*(3*k-1)/2).
Original entry on oeis.org
1, -1, -4, -8, 1, 24, 78, 111, 75, -249, -876, -1847, -2251, -871, 5170, 17052, 34742, 47176, 34576, -44016, -224561, -530104, -875149, -1030871, -475480, 1488315, 5658668, 12109163, 19411024, 22693048, 12926630, -24000623, -102605376, -230257606, -386964449
Offset: 0
A295121
Expansion of Product_{k>=1} 1/(1 + x^k)^(k*(2*k-1)).
Original entry on oeis.org
1, -1, -5, -10, 3, 42, 124, 160, 15, -677, -1941, -3425, -2807, 3488, 21004, 49547, 77879, 63395, -65104, -406091, -988889, -1655508, -1779329, -145347, 5087175, 15405270, 30158849, 42617486, 36116136, -19457047, -161973496, -418712896, -759063566
Offset: 0
A295122
Expansion of Product_{k>=1} 1/(1 + x^k)^(k*(5*k-3)/2).
Original entry on oeis.org
1, -1, -6, -12, 6, 65, 179, 202, -137, -1392, -3492, -5135, -1325, 15437, 52934, 101787, 116827, -16945, -462603, -1350732, -2475989, -2889620, -343236, 8559858, 26972213, 53099230, 72521956, 47535918, -86985043, -409729146, -952305325, -1577038736
Offset: 0
A295123
Expansion of Product_{k>=1} 1/(1 + x^k)^(k*(3*k-2)).
Original entry on oeis.org
1, -1, -7, -14, 10, 93, 242, 229, -410, -2446, -5500, -6458, 4062, 38899, 104715, 165843, 103045, -327200, -1393131, -3075317, -4305200, -2069461, 9129361, 35219829, 75832840, 109569915, 74818084, -143480059, -686408279, -1607860793, -2614721006, -2674073316
Offset: 0
Comments