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 14 results. Next

A062795 Duplicate of A062363.

Original entry on oeis.org

0, 1, 3, 7, 27, 121, 729, 5041, 40347, 362887, 3628923, 39916801, 479002353
Offset: 0

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Author

Keywords

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

A093804 Primes p such that p! + 1 is also prime.

Original entry on oeis.org

2, 3, 11, 37, 41, 73, 26951, 110059, 150209
Offset: 1

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Author

Jason Earls, May 19 2004

Keywords

Comments

Or, numbers n such that Sum_{d|n} d! is prime.
The prime 26951 from A002981 (n!+1 is prime) is a member since Sum_{d|n} d! = n!+1 if n is prime. - Jonathan Sondow, Jan 30 2005
a(n) are the primes in A002981[n] = {0, 1, 2, 3, 11, 27, 37, 41, 73, 77, 116, 154, 320, 340, 399, 427, 872, 1477, 6380, 26951, ...} Numbers n such that n! + 1 is prime. Corresponding primes of the form p! + 1 are listed in A103319[n] = {3, 7, 39916801, 13763753091226345046315979581580902400000001, 33452526613163807108170062053440751665152000000001, ...}. - Alexander Adamchuk, Sep 23 2006

Examples

			Sum_{d|3} d! = 1! + 3! = 7 is prime, so 3 is a member.
		

Crossrefs

Programs

Extensions

One more term from Alexander Adamchuk, Sep 23 2006
a(8)=110059 (found on Jun 11 2011, by PrimeGrid), added by Arkadiusz Wesolowski, Jun 28 2011
a(9)=150209 (found on Jun 09 2012, by Rene Dohmen), added by Jinyuan Wang, Jan 20 2020

A163079 Primes p such that p$ + 1 is also prime. Here '$' denotes the swinging factorial function (A056040).

Original entry on oeis.org

2, 3, 5, 31, 67, 139, 631, 9743, 16253, 17977, 27901, 37589
Offset: 1

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Author

Peter Luschny, Jul 21 2009

Keywords

Comments

a(n) are the primes in A163077.

Examples

			5 is prime and 5$ + 1 = 30 + 1 = 31 is prime, so 5 is in the sequence.
		

Crossrefs

Programs

  • Maple
    a := proc(n) select(isprime,select(k -> isprime(A056040(k)+1),[$0..n])) end:
  • Mathematica
    f[n_] := 2^(n - Mod[n, 2])*Product[k^((-1)^(k + 1)), {k, n}]; p = 2; lst = {}; While[p < 38000, a = f@p + 1; If[ PrimeQ@a, AppendTo[ lst, p]; Print@p]; p = NextPrime@p]; lst (* Robert G. Wilson v, Aug 08 2010 *)
  • PARI
    is(k) = isprime(k) && ispseudoprime(1+k!/(k\2)!^2); \\ Jinyuan Wang, Mar 22 2020

Extensions

a(8)-a(12) from Robert G. Wilson v, Aug 08 2010

A217576 a(n) = Sum_{d divides n} (d!)^(n/d).

Original entry on oeis.org

1, 3, 7, 29, 121, 765, 5041, 40913, 363097, 3643233, 39916801, 479535185, 6227020801, 87203692929, 1307676103777, 20924415922433, 355687428096001, 6402505760917569, 121645100408832001, 2432915176581403649, 51090942299733783937, 1124002321128529922049
Offset: 1

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Author

Joerg Arndt, Oct 07 2012

Keywords

Crossrefs

Cf. A062363 ( Sum_{d divides n} d! ).
Cf. A062796 ( Sum_{d divides n} d^d ), A066108 ( Sum_{d divides n} n^d ).

Programs

  • Mathematica
    f[n_]=With[{d=Divisors[n]},Total[(d!)^(n/d)]]; Array[f,25] (* Harvey P. Dale, Dec 20 2023 *)
  • PARI
    a(n)=sumdiv(n,d, (d!)^(n/d) );

Formula

G.f.: Sum_{n>=1} n!*x^n / (1 - n!*x^n). - Paul D. Hanna, Jan 17 2013

A348146 a(n) = Sum_{d|n} (d!)^(n-d).

Original entry on oeis.org

1, 2, 2, 6, 2, 234, 2, 331842, 46658, 24883200258, 2, 139314179589392898, 2, 82606411253903523840004098, 619173642242176782338, 6984964247141514123665660725036072962, 2, 109110688415571335888754861121236891599318185050114, 2
Offset: 1

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Author

Wesley Ivan Hurt, Oct 02 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[(i!)^(n - i) (1 - Ceiling[n/i] + Floor[n/i]), {i, n}], {n, 20}]
  • PARI
    a(n) = sumdiv(n, d, d!^(n-d)); \\ Seiichi Manyama, Oct 03 2021
    
  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=1, N, x^k/(1-(k!*x)^k))) \\ Seiichi Manyama, Oct 03 2021

Formula

a(p) = 2 for primes p.
G.f.: Sum_{k>=1} x^k/(1 - (k! * x)^k). - Seiichi Manyama, Oct 03 2021

A351708 a(n) = Sum_{p|n, p prime} (n/p)!.

Original entry on oeis.org

0, 1, 1, 2, 1, 8, 1, 24, 6, 122, 1, 744, 1, 5042, 126, 40320, 1, 363600, 1, 3628824, 5046, 39916802, 1, 479041920, 120, 6227020802, 362880, 87178291224, 1, 1307677997520, 1, 20922789888000, 39916806, 355687428096002, 5160, 6402374184729600, 1
Offset: 1

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Author

Wesley Ivan Hurt, Feb 16 2022

Keywords

Examples

			a(6) = 8; a(6) = Sum_{p|6} (6/p)! = (6/2)! + (6/3)! = 3*2 + 2*1 = 8.
		

Crossrefs

Programs

  • Maple
    f:= proc(n) local p;
      add((n/p)!, p = numtheory:-factorset(n))
    end proc:
    map(f, [$1..40]); # Robert Israel, Dec 05 2022
  • Mathematica
    Table[DivisorSum[n, Factorial[n/#] &, PrimeQ], {n, 36}] (* Michael De Vlieger, Dec 06 2022 *)

Formula

a(A000040(n)) = 1.

A321521 a(n) = Sum_{d|n} (-1)^(n/d+1)*d!.

Original entry on oeis.org

1, 1, 7, 21, 121, 715, 5041, 40293, 362887, 3628681, 39916801, 479000895, 6227020801, 87178286161, 1307674368127, 20922789847653, 355687428096001, 6402373705365835, 121645100408832001, 2432902008173011101, 51090942171709445047, 1124000727777567763201
Offset: 1

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Author

Ilya Gutkovskiy, Nov 12 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[(-1)^(n/d + 1) d!, {d, Divisors[n]}], {n, 22}]
    nmax = 22; Rest[CoefficientList[Series[Sum[k! x^k/(1 + x^k), {k, 1, nmax}], {x, 0, nmax}], x]]
  • PARI
    a(n) = sumdiv(n, d, (-1)^(n/d+1)*d!); \\ Michel Marcus, Nov 12 2018

Formula

G.f.: Sum_{k>=1} k!*x^k/(1 + x^k).
a(n) ~ n!. - Vaclav Kotesovec, Nov 13 2018

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).

A351709 a(n) = Sum_{p|n, p prime} p!.

Original entry on oeis.org

0, 2, 6, 2, 120, 8, 5040, 2, 6, 122, 39916800, 8, 6227020800, 5042, 126, 2, 355687428096000, 8, 121645100408832000, 122, 5046, 39916802, 25852016738884976640000, 8, 120, 6227020802, 6, 5042, 8841761993739701954543616000000, 128, 8222838654177922817725562880000000
Offset: 1

Views

Author

Wesley Ivan Hurt, Feb 16 2022

Keywords

Comments

Inverse Möbius transform of n! * c(n), where c(n) is the characteristic function of primes (A010051). - Wesley Ivan Hurt, Apr 01 2025

Examples

			a(6) = 8; a(6) = Sum_{p|6} p! = 2! + 3! = 2*1 + 3*2*1 = 8.
		

Crossrefs

Formula

a(n) = Sum_{d|n} d! * c(d), where c = A010051. - Wesley Ivan Hurt, Apr 01 2025
Showing 1-10 of 14 results. Next