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 1-4 of 4 results.

A113869 Coefficients in asymptotic expansion of probability that a random pair of elements from the alternating group A_k generates all of A_k.

Original entry on oeis.org

1, -1, -1, -4, -23, -171, -1542, -16241, -194973, -2622610, -39027573, -636225591, -11272598680, -215668335091, -4431191311809, -97316894892644, -2275184746472827, -56421527472282127, -1479397224086870294, -40897073524132164189, -1188896226524012279617
Offset: 0

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Author

N. J. A. Sloane, Jan 26 2006

Keywords

Crossrefs

Programs

Formula

The probability that a random pair of elements from the alternating group A_k generates all of A_k is P_k ~ 1-1/k-1/k^2-4/k^3-23/k^4-171/k^5-... = Sum_{n >= 0} a(n)/k^n.
Furthermore, P_k ~ 1 - Sum_{n >= 1} A003319(n)/[k]n, where [k]_n = k(k-1)(k-2)...(k-n+1). Therefore for n >= 2, a(n) = - Sum{i=1..n} A003319(i)*Stirling_2(n-1, i-1). - N. J. A. Sloane.
a(n) ~ -n! / (4 * (log(2))^(n+1)). - Vaclav Kotesovec, Jul 28 2015

A316084 Product_{k>=1} 1/(1 - a(k)*x^k) = Sum_{k>=0} k!*x^k.

Original entry on oeis.org

1, 1, 4, 17, 92, 566, 4156, 34023, 314348, 3195658, 35703996, 433259908, 5687955724, 80248240822, 1211781628060, 19496367748659, 333041104402860, 6019720779293770, 114794574818830716, 2303327555284622304, 48509766568956367372, 1069982619999485015070
Offset: 1

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Author

Seiichi Manyama, Jun 23 2018

Keywords

Examples

			1/((1-x)*(1-x^2)*(1-4*x^3)*(1-17*x^4)* ... ) = 1 + x + 2*x^2 + 6*x^3 + 24*x^4 + ... .
		

Crossrefs

Formula

a(n) ~ n! * (1 - 1/n - 1/n^2 - 4/n^3 - 23/n^4 - 171/n^5 - 1542/n^6 - 16241/n^7 - 194973/n^8 - 2622610/n^9 - 39027573/n^10 - ...), for coefficients see A113869. - Vaclav Kotesovec, Jun 18 2019
a(2*n-1) = A158094(2*n-1). - Vaclav Kotesovec, Jun 18 2019

A316083 Product_{k>=1} (1 + a(k)*x^k) = Sum_{k>=0} (k*x)^k.

Original entry on oeis.org

1, 4, 23, 233, 2800, 42832, 763220, 15761709, 366711200, 9537738596, 273549419552, 8587897407548, 292755986184548, 10773140836162944, 425587704331945152, 17966341563465800813, 807152054953801845760, 38451432814472749509872, 1936082850634342992601636
Offset: 1

Views

Author

Seiichi Manyama, Jun 23 2018

Keywords

Examples

			(1+x)*(1+4*x^2)*(1+23*x^3)*(1+233*x^4)* ... = 1 + x + 4*x^2 + 27*x^3 + 256*x^4 + ... .
		

Crossrefs

Formula

a(n) ~ n^n. - Vaclav Kotesovec, Jun 18 2019

A363254 Product_{n>=1} (1 + a(n)*x^n) = 1 + 1!!*x + 3!!*x^2 + 5!!*x^3 + 7!!*x^4 + ...

Original entry on oeis.org

1, 3, 12, 93, 816, 9264, 122028, 1863849, 32001504, 614224272, 12989299596, 300599511744, 7550646317520, 204694926767040, 5955892801274796, 185160666502244433, 6125200081143892800, 214838236392631067424, 7963817560398871790604, 311101474513327693885056
Offset: 1

Views

Author

Ilya Gutkovskiy, May 23 2023

Keywords

Crossrefs

Programs

  • Mathematica
    A[m_, n_] := A[m, n] = Which[m == 1, (2 n - 1)!!, m > n >= 1, 0, True, A[m - 1, n] - A[m - 1, m - 1] A[m, n - m + 1]]; a[n_] := A[n, n]; a /@ Range[1, 20]
Showing 1-4 of 4 results.