A300581
Expansion of Product_{k>=1} 1/(1 - 2^(k+1)*x^k).
Original entry on oeis.org
1, 4, 24, 112, 544, 2368, 10624, 44800, 190976, 791552, 3282944, 13414400, 54829056, 222117888, 899383296, 3625123840, 14601027584, 58659700736, 235555782656, 944552017920, 3786334535680, 15166305468416, 60736264994816, 243129089261568, 973133053952000
Offset: 0
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nmax = 25; CoefficientList[Series[Product[1/(1-2^(k+1)*x^k), {k, 1, nmax}], {x, 0, nmax}], x]
A323634
Expansion of Product_{k>=1} 1/(1 - k^(k-1)*x^k).
Original entry on oeis.org
1, 1, 3, 12, 80, 723, 8716, 128227, 2251086, 45647542, 1051845574, 27107414480, 772785074811, 24136982014698, 819697939365724, 30068912837398063, 1184872370227462528, 49914074776385885492, 2238476211786621770206, 106476394492364281869654, 5354276181476337307494676
Offset: 0
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a:=series(mul(1/(1-k^(k-1)*x^k),k=1..100),x=0,21): seq(coeff(a,x,n),n=0..20); # Paolo P. Lava, Apr 02 2019
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nmax = 20; CoefficientList[Series[Product[1/(1 - k^(k - 1) x^k), {k, 1, nmax}], {x, 0, nmax}], x]
a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d^(k - k/d + 1), {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 20}]
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N=40; x='x+O('x^N); Vec(1/prod(k=1, N, 1-k^(k-1)*x^k)) \\ Seiichi Manyama, Aug 22 2020
A294946
Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of exp(Sum_{j>0} sigma_k(j)*x^j/j) in powers of x.
Original entry on oeis.org
1, 1, 1, 1, 1, 3, 1, 1, 5, 12, 1, 1, 9, 32, 82, 1, 1, 17, 90, 304, 725, 1, 1, 33, 260, 1162, 3537, 8811, 1, 1, 65, 762, 4516, 17435, 52010, 128340, 1, 1, 129, 2252, 17722, 86529, 310193, 895397, 2257687, 1, 1, 257, 6690, 69964, 431675, 1865766, 6286826, 18016416, 45658174
Offset: 0
Square array begins:
1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, ...
3, 5, 9, 17, 33, ...
12, 32, 90, 260, 762, ...
82, 304, 1162, 4516, 17722, ...
725, 3537, 17435, 86529, 431675, ...
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