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 1-10 of 11 results. Next

A248871 Coefficients in asymptotic expansion of sequence A107895.

Original entry on oeis.org

1, 1, 3, 12, 66, 450, 3679, 35260, 388511, 4844584, 67502450, 1039929756, 17556193609, 322321551868, 6393505020803, 136245752898586, 3103879644045050, 75268872986970840, 1935571325829192247, 52605265683008056660, 1506530437404419817467
Offset: 0

Views

Author

Vaclav Kotesovec, Mar 14 2015

Keywords

Examples

			A107895(n) / n! ~ 1 + 1/n + 3/n^2 + 12/n^3 + 66/n^4 + 450/n^5 + 3679/n^6 + ...
		

Crossrefs

Formula

a(k) ~ k! / (4 * (log(2))^(k+1)).

A179327 G.f.: Product_{n>=1} 1/(1-x^n)^((n-1)!).

Original entry on oeis.org

1, 1, 2, 4, 11, 37, 167, 925, 6164, 47630, 418227, 4105887, 44529413, 528398441, 6807143686, 94588353184, 1409913624333, 22437692156739, 379673925360239, 6806484898946045, 128862141334488784, 2569079946351669286, 53797816061915662161, 1180533553597621952193
Offset: 0

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Author

Paul D. Hanna, Jan 08 2011

Keywords

Examples

			G.f.: A(x) = 1 + x + 2*x^2 + 4*x^3 + 11*x^4 + 37*x^5 + 167*x^6 +...
A(x) = 1/((1-x)*(1-x^2)*(1-x^3)^2*(1-x^4)^6*(1-x^5)^24*(1-x^6)^120*...).
log(A(x)) = x + 3*x^2/2 + 7*x^3/3 + 27*x^4/4 + 121*x^5/5 + 729*x^6/6 + 5041*x^7/7 + 40347*x^8/8 +...+ A062363(n)*x^n/n +...
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(b(n-i*j, i-1)*binomial((i-1)!+j-1, j), j=0..n/i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..23);  # Alois P. Heinz, Aug 10 2021
  • Mathematica
    nmax=20; CoefficientList[Series[Product[1/(1-x^k)^((k-1)!),{k,1,nmax}],{x,0,nmax}],x] (* Vaclav Kotesovec, Mar 14 2015 *)
  • PARI
    {a(n)=polcoeff(exp(sum(m=1,n,sumdiv(m,d,d!)*x^m/m)+x*O(x^n)),n)}

Formula

Euler transform of (n-1)!.
G.f.: A(x) = exp( Sum_{n>=1} A062363(n)*x^n/n ) where A062363(n) = Sum_{d|n} d!.
a(n) ~ (n-1)! * (1 + 1/n + 3/n^2 + 11/n^3 + 50/n^4 + 278/n^5 + 1860/n^6 + 14793/n^7 + 138166/n^8 + 1494034/n^9 + 18422609/n^10), for coefficients see A256126. - Vaclav Kotesovec, Mar 14 2015

A261052 Expansion of Product_{k>=1} (1+x^k)^(k!).

Original entry on oeis.org

1, 1, 2, 8, 31, 157, 915, 6213, 48240, 423398, 4147775, 44882107, 531564195, 6837784087, 94909482330, 1413561537884, 22482554909451, 380269771734265, 6815003300096013, 128992737080703803, 2571218642722865352, 53835084737513866662, 1181222084520177393143
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 08 2015

Keywords

Comments

Weigh transform of the factorial numbers. - Alois P. Heinz, Jun 11 2018

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
          add(binomial(i!, j)*b(n-i*j,i-1), j=0..n/i)))
        end:
    a:= n-> b(n$2):
    seq(a(n), n=0..25);  # Alois P. Heinz, Aug 08 2015
  • Mathematica
    nmax=25; CoefficientList[Series[Product[(1+x^k)^(k!),{k,1,nmax}],{x,0,nmax}],x]
  • PARI
    seq(n)={Vec(exp(x*Ser(dirmul(vector(n, n, n!), -vector(n, n, (-1)^n/n)))))} \\ Andrew Howroyd, Jun 22 2018

Formula

a(n) ~ n! * (1 + 1/n + 2/n^2 + 10/n^3 + 57/n^4 + 401/n^5 + 3382/n^6 + 33183/n^7 + 371600/n^8 + 4685547/n^9 + 65792453/n^10).

A107894 Sum over the products of factorials of parts in all partitions of n where the sum runs over the number of different parts only.

Original entry on oeis.org

1, 1, 3, 9, 35, 167, 943, 6379, 48945, 429651, 4189865, 45307601, 535518109, 6883110373, 95435065935, 1420468921893, 22577620176887, 381695573051099, 6837601709298811, 129375694813679215, 2578070946813526485, 53964818587883937807, 1183805926540690127573
Offset: 0

Views

Author

Thomas Wieder, May 26 2005

Keywords

Examples

			The partitions of 5 are 1+1+1+1+1, 1+1+1+2, 1+1+3, 1+2+2, 1+4, 2+3, 5, the corresponding products of factorials of parts are (when multiple parts are counted once only) 1!, 1!*2!, 1!*3!, 1!*2!, 1!*4!, 2!*3!, 5! and their sum is a(5) = 167.
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember;
          `if`(n=0 or i<2, 1, b(n, i-1) +i!*add(b(n-i*j, i-1), j=1..n/i))
        end:
    a:= n-> b(n, n):
    seq(a(n), n=0..30); # Alois P. Heinz, Apr 04 2012
  • Mathematica
    Total[Times@@@(Union/@IntegerPartitions[#]!)]&/@Range[20]  (* Harvey P. Dale, Feb 26 2011 *)
    b[n_, i_] := b[n, i] = If[n==0 || i<2, 1, b[n, i-1] + i!*Sum[b[n-i*j, i-1], {j, 1, n/i}]]; a[n_] := b[n, n]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Oct 29 2015, after Alois P. Heinz *)

Formula

a(n) ~ n! * (1 + 1/n + 3/n^2 + 12/n^3 + 65/n^4 + 443/n^5 + 3626/n^6 + 34811/n^7 + 384479/n^8 + 4806098/n^9 + 67109281/n^10), for coefficients see A256124. - Vaclav Kotesovec, Mar 15 2015

Extensions

a(0) inserted and more terms from Alois P. Heinz, Apr 04 2012

A261047 Euler transform of (n+1)!.

Original entry on oeis.org

1, 2, 9, 40, 212, 1248, 8400, 63576, 540858, 5132564, 53952742, 623324184, 7855144818, 107224120980, 1575511525794, 24784246515256, 415435624535225, 7389692971336602, 138992875726543381, 2755750468146310688, 57433108983590606292
Offset: 0

Views

Author

Vaclav Kotesovec, Aug 08 2015

Keywords

Crossrefs

Programs

  • Maple
    a:= proc(n) option remember; `if`(n=0, 1, add(add(d*
         (d+1)!, d=numtheory[divisors](j))*a(n-j), j=1..n)/n)
        end:
    seq(a(n), n=0..30);  # Alois P. Heinz, Jul 28 2017
  • Mathematica
    nmax=20; CoefficientList[Series[Product[1/(1-x^k)^((k+1)!), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

a(n) ~ (n+1)! * (1 + 2/n + 7/n^2 + 33/n^3 + 219/n^4 + 1705/n^5 + 15707/n^6 + 166289/n^7 + 1993141/n^8 + 26727125/n^9 + 397081369/n^10).
a(n) ~ n! * n * (1 + 3/n + 9/n^2 + 40/n^3 + 252/n^4 + 1924/n^5 + 17412/n^6 + 181996/n^7 + 2159430/n^8 + 28720266/n^9 + 423808494/n^10).

A305867 Expansion of Product_{k>=1} 1/(1 - x^k)^(2*k-1)!!.

Original entry on oeis.org

1, 1, 4, 19, 130, 1120, 11960, 151595, 2230550, 37361755, 701873371, 14610774346, 333746628499, 8298025724194, 223049950124065, 6444634486214748, 199165237980655863, 6555102341516877027, 228905611339161301812, 8452656930719845696590, 329075775511339959533232, 13471099892869946627980017
Offset: 0

Views

Author

Ilya Gutkovskiy, Jun 12 2018

Keywords

Comments

Euler transform of A001147.

Crossrefs

Programs

  • Maple
    N:= 25:
    S:=series(mul((1-x^k)^(-doublefactorial(2*k-1)),k=1..N),x,N+1):
    seq(coeff(S,x,n),n=0..N); # Robert Israel, Jun 12 2018
  • Mathematica
    nmax = 21; CoefficientList[Series[Product[1/(1 - x^k)^(2 k - 1)!!, {k, 1, nmax}], {x, 0, nmax}], x]
    a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d (2 d - 1)!!, {d, Divisors[k]}] a[n - k], {k, 1, n}]/n]; Table[a[n], {n, 0, 21}]

Formula

G.f.: Product_{k>=1} 1/(1 - x^k)^A001147(k).

A280088 Expansion of Product_{k>=1} 1/(1 - x^k)^(k!!).

Original entry on oeis.org

1, 1, 3, 6, 17, 38, 112, 280, 882, 2416, 8253, 24458, 91051, 289704, 1172288, 3980034, 17413820, 62706119, 294608079, 1118820630, 5603910081, 22328924231, 118432939871, 492897768426, 2752203529333, 11918139966134, 69709167028426, 313080284080648, 1910245872252972, 8873669214476627, 56283324138424814, 269790676411694902
Offset: 0

Views

Author

Ilya Gutkovskiy, Dec 25 2016

Keywords

Comments

Euler transform of the double factorials (A006882).

Crossrefs

Programs

  • Mathematica
    nmax = 31; CoefficientList[Series[Product[1/(1 - x^k)^(k!!), {k, 1, nmax}], {x, 0, nmax}], x]

Formula

G.f.: Product_{k>=1} 1/(1 - x^k)^(k!!).
a(n) ~ n!!. - Vaclav Kotesovec, Dec 25 2016

A321875 a(n) = Sum_{d|n} d*d!.

Original entry on oeis.org

1, 5, 19, 101, 601, 4343, 35281, 322661, 3265939, 36288605, 439084801, 5748023639, 80951270401, 1220496112085, 19615115520619, 334764638530661, 6046686277632001, 115242726706374263, 2311256907767808001, 48658040163569088701, 1072909785605898275299
Offset: 1

Views

Author

Ilya Gutkovskiy, Nov 20 2018

Keywords

Comments

Inverse Möbius transform of A001563.

Crossrefs

Programs

  • Magma
    m:=25; R:=PowerSeriesRing(Integers(), m); Coefficients(R!( (&+[k*Factorial(k)*x^k/(1 - x^k): k in [1..(m+2)]]) )); // G. C. Greubel, Nov 20 2018
    
  • Mathematica
    Table[Sum[d d!, {d, Divisors[n]}], {n, 21}]
    nmax = 21; Rest[CoefficientList[Series[Sum[k k! x^k/(1 - x^k), {k, 1, nmax}], {x, 0, nmax}], x]]
    nmax = 21; Rest[CoefficientList[Series[-Log[Product[(1 - x^k)^k!, {k, 1, nmax}]], {x, 0, nmax}], x] Range[0, nmax]]
  • PARI
    a(n) = sumdiv(n, d, d*d!); \\ Michel Marcus, Nov 20 2018
    
  • Sage
    s = sum(k*factorial(k)*x^k/(1-x^k) for k in (1..24));
    (s/x).series(x, 21).coefficients(x, sparse=false) # Peter Luschny, Nov 21 2018

Formula

G.f.: Sum_{k>=1} k*k!*x^k/(1 - x^k).
L.g.f.: -log(Product_{k>=1} (1 - x^k)^(k!)) = Sum_{n>=1} a(n)*x^n/n.
a(n) = Sum_{d|n} A001563(d).

A380497 Euler transform of primorial numbers.

Original entry on oeis.org

1, 2, 9, 46, 314, 3072, 37641, 603510, 11148030, 249327430, 7040987792, 216220333314, 7895699690498, 321315600822232, 13770543972819903, 644232544408157820, 33954066516677635554, 1994206929690480710244, 121461036181617491970561, 8111955386813996410196454, 574814471423312085719652432
Offset: 0

Views

Author

Ilya Gutkovskiy, Jan 25 2025

Keywords

Crossrefs

Programs

  • Maple
    p:= proc(n) option remember; `if`(n<1, 1, p(n-1)*ithprime(n)) end:
    a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)*
          add(d*p(d), d=numtheory[divisors](j)), j=1..n)/n)
        end:
    seq(a(n), n=0..20);  # Alois P. Heinz, Jan 25 2025
  • Mathematica
    nmax = 20; CoefficientList[Series[Product[1/(1 - x^k)^Product[Prime[j], {j, k}], {k, 1, nmax}], {x, 0, nmax}], x]
    primorial[n_] := Product[Prime[j], {j, 1, n}]; a[n_] := a[n] = If[n == 0, 1, Sum[Sum[d primorial[d], {d, Divisors[j]}] a[n - j], {j, 1, n}]/n]; Table[a[n], {n, 0, 20}]

Formula

G.f.: Product_{k>=1} 1 / (1 - x^k)^prime(k)#.

A053483 Euler transform of A029767.

Original entry on oeis.org

1, 4, 18, 114, 900, 8845, 103861, 1427122, 22486706, 399906140, 7922936720, 173013117604, 4127746294408, 106806183646594, 2978731438384738, 89065499057526433, 2842061902985159593, 96395720127638538076, 3462922846509648162418
Offset: 0

Views

Author

N. J. A. Sloane, Jan 15 2000

Keywords

Crossrefs

Cf. A107895.

Programs

  • Mathematica
    Rest[CoefficientList[Series[Product[1/(1 - x^k)^((k-1)!*(2^k-1)), {k, 1, 20}], {x, 0, 20}], x]] (* Vaclav Kotesovec, Aug 07 2015 *)
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