A053503
Number of degree-n permutations of order dividing 16.
Original entry on oeis.org
1, 1, 2, 4, 16, 56, 256, 1072, 11264, 78976, 672256, 4653056, 49810432, 433429504, 4448608256, 39221579776, 1914926104576, 29475151020032, 501759779405824, 6238907914387456, 120652091860975616, 1751735807564578816, 29062253310781161472, 398033706586943258624
Offset: 0
- R. P. Stanley, Enumerative Combinatorics, Cambridge, Vol. 2, 1999; see Example 5.2.10.
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m:=30; R:=PowerSeriesRing(Rationals(), m); b:=Coefficients(R!( Exp(x + x^2/2 + x^4/4 + x^8/8 + x^16/16) )); [Factorial(n-1)*b[n]: n in [1..m]]; // G. C. Greubel, May 15 2019
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a:= proc(n) option remember; `if`(n<0, 0, `if`(n=0, 1,
add(mul(n-i, i=1..2^j-1)*a(n-2^j), j=0..4)))
end:
seq(a(n), n=0..25); # Alois P. Heinz, Feb 14 2013
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a[n_]:= a[n] =If[n<0, 0, If[n==0, 1, Sum[Product[n-i, {i, 1, 2^j-1}]* a[n-2^j], {j, 0, 4}]]]; Table[a[n], {n, 0, 25}] (* Jean-François Alcover, Mar 19 2014, after Alois P. Heinz *)
With[{m = 30}, CoefficientList[Series[Exp[x +x^2/2 +x^4/4 +x^8/8 + x^16/16], {x, 0, m}], x]*Range[0, m]!] (* G. C. Greubel, May 15 2019 *)
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my(x='x+O('x^30)); Vec(serlaplace( exp(x + x^2/2 + x^4/4 + x^8/8 + x^16/16) )) \\ G. C. Greubel, May 15 2019
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m = 30; T = taylor(exp(x + x^2/2 + x^4/4 + x^8/8 + x^16/16), x, 0, m); [factorial(n)*T.coefficient(x, n) for n in (0..m)] # G. C. Greubel, May 15 2019
A218003
Number of degree-n permutations of order a power of 3.
Original entry on oeis.org
1, 1, 1, 3, 9, 21, 81, 351, 1233, 46089, 434241, 2359611, 27387801, 264333213, 1722161169, 16514298711, 163094452641, 1216239520401, 50883607918593, 866931703203699, 8473720481213481, 166915156382509221, 2699805625227141201, 28818706120636531023, 439756550972215638129, 6766483260087819272601, 77096822666547068590401, 406859605390184444341678251
Offset: 0
E.g.f.: A(x) = 1 + x + x^2/2! + 3*x^3/3! + 9*x^4/4! + 21*x^5/5! + 81*x^6/6! +...
where
log(A(x)) = x + x^3/3 + x^9/9 + x^27/27 + x^81/81 +...+ x^3^n/3^n +...
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a:= proc(n) option remember; `if`(n<0, 0, `if`(n=0, 1,
add(mul(n-i, i=1..3^j-1)*a(n-3^j), j=0..ilog[3](n))))
end:
seq(a(n), n=0..30); # Alois P. Heinz, Jan 25 2014
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a[n_] := a[n] = If[n < 0, 0, If[n == 0, 1, Sum[Product[n-i, {i, 1, 3^j-1}]*a[n-3^j], {j, 0, Floor@Log[3, n]}]]];
Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Apr 28 2025, after Alois P. Heinz *)
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{a(n)=n!*polcoeff(exp(sum(k=0,ceil(log(n+1)/log(3)),x^(3^k)/3^k)+x*O(x^n)),n)}
for(n=0,30,print1(a(n),", "))
A308392
Expansion of e.g.f. exp(x + 2 * Sum_{k>=1} x^(2^k)/2^k).
Original entry on oeis.org
1, 1, 3, 7, 37, 141, 871, 4243, 42057, 285337, 3008971, 23292831, 295839853, 2733811237, 35818366767, 360892885291, 8394097115281, 113063153955633, 2347668770502547, 32362689647446327, 744513384520939701, 11439249110436735421, 245772094687992577783, 3860080495614830875587
Offset: 0
-
nmax = 23; CoefficientList[Series[Exp[x + 2 Sum[x^(2^k)/2^k, {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
nmax = 23; CoefficientList[Series[Product[(1 - x^k)^((-1)^k MoebiusMu[k]/k), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
A374346
E.g.f. A(x) satisfies A(x) = A(x^2)^(1/2) * exp(2*x) with A(0)=1.
Original entry on oeis.org
1, 2, 6, 20, 88, 432, 2464, 14912, 111360, 912896, 8491264, 80905728, 861835264, 9524264960, 113218762752, 1362387243008, 20665650774016, 337892698226688, 6100999266304000, 106342541313572864, 2014622956858638336, 37864490015441027072
Offset: 0
A374364
Expansion of e.g.f. exp( x - Sum_{k>=1} x^(2^k)/2^k ).
Original entry on oeis.org
1, 1, 0, -2, -8, -24, 16, 400, -3072, -38528, -18944, 1287936, 17843200, 149045248, -188786688, -12007184384, -1265929355264, -20275964313600, 3871935889408, 2355175169523712, 45658709327609856, 565591105847689216, -1448855443865600000
Offset: 0
A308461
Expansion of e.g.f. exp(x + 2 * Sum_{k>=2} x^(2^k)/2^k).
Original entry on oeis.org
1, 1, 1, 1, 13, 61, 181, 421, 15961, 137593, 682921, 2498761, 77344741, 927575221, 6402167773, 31881065581, 4104839160241, 68050288734961, 609856397747281, 3857727706737553, 222655237411428541, 4351842324095032621, 47276537013742616581, 361153046139022585141
Offset: 0
-
nmax = 23; CoefficientList[Series[Exp[x + 2 Sum[x^(2^k)/2^k, {k, 2, nmax}]], {x, 0, nmax}], x] Range[0, nmax]!
nmax = 23; CoefficientList[Series[Product[(1 + (-x)^k)^((-1)^k MoebiusMu[k]/k), {k, 1, nmax}], {x, 0, nmax}], x] Range[0, nmax]!
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