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.

Previous Showing 11-20 of 20 results.

A008786 a(n) = (n+5)^n.

Original entry on oeis.org

1, 6, 49, 512, 6561, 100000, 1771561, 35831808, 815730721, 20661046784, 576650390625, 17592186044416, 582622237229761, 20822964865671168, 799006685782884121, 32768000000000000000, 1430568690241985328321, 66249952919459433152512, 3244150909895248285300369
Offset: 0

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Author

Keywords

Crossrefs

Programs

Formula

E.g.f.(x) for b(n) = n^(n-5) = a(n-5): T - (15/16)*T^2 + (85/216)T^3 - (25/288)*T^4 + (1/120)*T^5, where T=T(x) is Euler's tree function. - Len Smiley, Nov 17 2001
E.g.f.: LambertW(-x)^5/((-x)^5*(1+LambertW(-x))). - Vladeta Jovovic, Nov 07 2003
E.g.f.: (1/4)*d/dx((LambertW(-x)/(-x))^4). - Wolfdieter Lang, Oct 25 2022

A008787 a(n) = (n + 6)^n.

Original entry on oeis.org

1, 7, 64, 729, 10000, 161051, 2985984, 62748517, 1475789056, 38443359375, 1099511627776, 34271896307633, 1156831381426176, 42052983462257059, 1638400000000000000, 68122318582951682301, 3011361496339065143296
Offset: 0

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Keywords

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Programs

Formula

E.g.f.(x) for b(n) = n^(n-6) = a(n-6): T - (31/32)*T^2 + (575/1296)*T^3 - (415/3456)*T^4 + (137/7200)*T^5 - (1/720)*T^6; where T=T(x) is Euler's tree function (see A000169). - Len Smiley, Nov 17 2001
E.g.f.: LambertW(-x)^6/(x^6*(1+LambertW(-x))). - Vladeta Jovovic, Nov 07 2003
E.g.f.: (1/5)*d/dx(LambertW(-x)/(-x))^5. - Wolfdieter Lang, Oct 25 2022

A008790 a(n) = n^(n+4).

Original entry on oeis.org

0, 1, 64, 2187, 65536, 1953125, 60466176, 1977326743, 68719476736, 2541865828329, 100000000000000, 4177248169415651, 184884258895036416, 8650415919381337933, 426878854210636742656, 22168378200531005859375
Offset: 0

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Programs

Formula

E.g.f.: T*(1 +22*T +58*T^2 +24*T^3)*(1-T)^(-9); where T is Euler's tree function (see A000169). - Len Smiley, Nov 17 2001
See A008517 and A134991 for similar e.g.f.s and diagonals of A048993. - Tom Copeland, Oct 03 2011
E.g.f.: d^4/dx^4 {x^4/(T(x)^4*(1-T(x)))}, where T(x) = Sum_{n>=1} n^(n-1)*x^n/n! is the tree function of A000169. - Peter Bala, Aug 05 2012

A350452 Number T(n,k) of endofunctions on [n] with exactly k connected components and no fixed points; triangle T(n,k), n>=0, 0<=k<=floor(n/2), read by rows.

Original entry on oeis.org

1, 0, 0, 1, 0, 8, 0, 78, 3, 0, 944, 80, 0, 13800, 1810, 15, 0, 237432, 41664, 840, 0, 4708144, 1022252, 34300, 105, 0, 105822432, 27098784, 1286432, 10080, 0, 2660215680, 778128336, 47790540, 648900, 945, 0, 73983185000, 24165049920, 1815578160, 36048320, 138600
Offset: 0

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Author

Alois P. Heinz, Dec 31 2021

Keywords

Comments

For k >= 2 and p prime, T(p,k) == 0 (mod 4*p*(p-1)). - Mélika Tebni, Jan 20 2023

Examples

			Triangle T(n,k) begins:
  1;
  0;
  0,          1;
  0,          8;
  0,         78,         3;
  0,        944,        80;
  0,      13800,      1810,       15;
  0,     237432,     41664,      840;
  0,    4708144,   1022252,    34300,    105;
  0,  105822432,  27098784,  1286432,  10080;
  0, 2660215680, 778128336, 47790540, 648900, 945;
  ...
		

Crossrefs

Columns k=0-1 give: A000007, A000435.
Row sums give A065440.
T(2n,n) gives A001147.

Programs

  • Maple
    c:= proc(n) option remember; add(n!*n^(n-k-1)/(n-k)!, k=2..n) end:
    b:= proc(n) option remember; expand(`if`(n=0, 1, add(
          b(n-i)*binomial(n-1, i-1)*x*c(i), i=1..n)))
        end:
    T:= n-> (p-> seq(coeff(p, x, i), i=0..n/2))(b(n)):
    seq(T(n), n=0..12);
  • Mathematica
    c[n_] := c[n] = Sum[n!*n^(n - k - 1)/(n - k)!, {k, 2, n}];
    b[n_] := b[n] = Expand[If[n == 0, 1, Sum[
         b[n - i]*Binomial[n - 1, i - 1]*x*c[i], {i, 1, n}]]];
    T[n_] := Function[p, Table[Coefficient[p, x, i], {i, 0, n/2}]][b[n]];
    Table[T[n], {n, 0, 12}] // Flatten (* Jean-François Alcover, Mar 18 2022, after Alois P. Heinz *)
  • PARI
    \\ here AS1(n,k) gives associated Stirling numbers of 1st kind.
    AS1(n,k)={(-1)^(n+k)*sum(i=0, k, (-1)^i * binomial(n, i) * stirling(n-i, k-i, 1) )}
    T(n,k) = {if(n==0, k==0, sum(j=k, n, n^(n-j)*binomial(n-1, j-1)*AS1(j,k)))} \\ Andrew Howroyd, Jan 20 2023

Formula

From Mélika Tebni, Jan 20 2023: (Start)
E.g.f. column k: (LambertW(-x) - log(1 + LambertW(-x)))^k / k!.
-Sum_{k=1..n/2} (-1)^k*T(n,k) = A071720(n+1), for n > 0.
-Sum_{k=1..n/2} (-1)^k*T(n,k) / (n-1) = A007830(n-2), for n > 1.
T(n,k) = Sum_{j=k..n} n^(n-j)*binomial(n-1, j-1)*A106828(j, k) for n > 0. (End)

A060348 a(n) = n^n * (n^2 - 1)/24.

Original entry on oeis.org

9, 160, 3125, 68040, 1647086, 44040192, 1291401630, 41250000000, 1426558353055, 53125098504192, 2120125746145771, 90285055457658880, 4087009643554687500, 195996655783163985920, 9926883142636041170124, 529537075346699234869248
Offset: 3

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Author

Noam Katz (noamkj(AT)hotmail.com), Mar 30 2001

Keywords

Comments

For n >= 3, a(n) is the number of nonequivalent primitive meromorphic functions with one pole of order n on a Riemann surface of genus 1.

References

  • B. Shapiro, M. Shapiro and A. Vainshtein, Ramified coverings of S^2 with one degenerate branching point and enumeration of edge-ordered graphs, Amer. Math. Soc. Transl., Vol. 180 (1997), pp. 219-227.

Crossrefs

Programs

  • PARI
    { for (n=3, 200, write("b060348.txt", n, " ", n^n * (n^2 - 1)/24); ) } \\ Harry J. Smith, Jul 04 2009

A060349 a(n) = n^(n+2)*(n^2 - 1)*(n+3)*(n+2)*(5*n - 7)/5760.

Original entry on oeis.org

81, 5824, 328125, 16901136, 847425747, 42630905856, 2186213819427, 115293750000000, 6283133610195442, 354769407810994176, 20781472563720847342, 1263485180096661430272, 79727340621643066406250, 5219469342167970210643968, 354305349685394263423480746
Offset: 3

Views

Author

Noam Katz (noamkj(AT)hotmail.com), Mar 30 2001

Keywords

Comments

For n >= 3, a(n) is the number of nonequivalent primitive meromorphic functions with one pole of order n on a Riemann surface of genus 2.

References

  • B. Shapiro, M. Shapiro and A. Vainshtein, Ramified coverings of S^2 with one degenerate branching point and enumeration of edge-ordered graphs, Amer. Math. Soc. Transl., Vol. 180 (1997), pp. 219-227.

Crossrefs

Programs

  • Mathematica
    Table[(n^(n+2) (n^2-1)(n+3)(n+2)(5n-7))/5760,{n,3,20}] (* Harvey P. Dale, Jan 10 2013 *)
  • PARI
    { for (n=3, 200, write("b060349.txt", n, " ", n^(n + 2)*(n^2 - 1)*(n + 3)*(n + 2)*(5*n - 7)/5760); ) } \\ Harry J. Smith, Jul 04 2009

A140647 Number of car parking assignments of n cars in n spaces, if one car does not park.

Original entry on oeis.org

1, 10, 107, 1346, 19917, 341986, 6713975, 148717762, 3674435393, 100284451730, 2998366140915, 97510068994690, 3428106725444117, 129590070259759042, 5242767731544271343, 226057515078414496898, 10350122253780835777545, 501543984793431059579122
Offset: 2

Views

Author

Jonathan Vos Post, Jul 09 2008

Keywords

Examples

			a(3) = 10: [1,3,3], [2,2,2], [2,2,3], [2,3,2], [2,3,3], [3,1,3], [3,2,2], [3,2,3], [3,3,1], [3,3,2].
		

Crossrefs

Cf. A000272.
Column k=1 of A264902.

Formula

a(n) = 2*(n+2)^(n-1)-(3*n+1)*(n+1)^(n-2). - Vladeta Jovovic, Jul 21 2008
a(n) = 2*A007830(n-1)-A016777(n)*A007830(n-2). - R. J. Mathar, Aug 09 2008
a(n) ~ (2*exp(2) - 3*exp(1)) * n^(n-1). - Vaclav Kotesovec, Aug 19 2017

Extensions

Extended beyond a(10) by R. J. Mathar, Aug 09 2008

A157994 Number of trees with n edges equipped with a cyclic order on their edges, i.e., number of orbits of the action of Z/nZ on the set of edge-labeled trees of size n, given by cyclically permuting the labels.

Original entry on oeis.org

1, 1, 2, 8, 44, 411, 4682, 66524, 1111134, 21437357, 469070942, 11488238992, 311505013052, 9267596377239, 300239975166840, 10523614185609344, 396861212733968144, 16024522976922760209, 689852631578947368422
Offset: 1

Views

Author

Nikos Apostolakis, Mar 10 2009

Keywords

Crossrefs

Programs

  • Sage
    [1,1] + [((n+1)^(n-2) + sum([(n+1)^(gcd(n,k) -1) for k in [1..n-1]]))/n for  n in [3..20]]

Formula

a(1) = 1, a(2) = 1, a(n) = (1/n)*((n+1)^{n-2} + sum_{k=1}^{n-1} (n+1)^{gcd(n,k)-1}) for n > 2

Extensions

Corrected the formula and Sage code - Nikos Apostolakis, Feb 27 2011.

A173249 Partial sums of A000272.

Original entry on oeis.org

1, 2, 3, 6, 22, 147, 1443, 18250, 280394, 5063363, 105063363, 2463011054, 64380375278, 1856540769315, 58550453144611, 2004745521503986, 74062339559431922, 2936485391069247715, 124376016487663499491
Offset: 0

Views

Author

Jonathan Vos Post, Feb 13 2010

Keywords

Comments

Partial sums of number of trees on n labeled nodes. The subsequence of primes in this sequence begin: 2, 58550453144611, no more through a(30).

Examples

			a(19) = 1 + 1 + 1 + 3 + 16 + 125 + 1296 + 16807 + 262144 + 4782969 + 100000000 + 2357947691 + 61917364224 + 1792160394037 + 56693912375296 + 1946195068359375 + 72057594037927936 + 2862423051509815793 + 121439531096594251776 + 5480386857784802185939.
		

Crossrefs

Formula

a(n) = SUM[i=0..n] A000272(i) = SUM[i=0..n] i^(i-2).

A364870 Array read by ascending antidiagonals: A(n, k) = (n + k)^n, with k >= 0.

Original entry on oeis.org

1, 1, 1, 4, 2, 1, 27, 9, 3, 1, 256, 64, 16, 4, 1, 3125, 625, 125, 25, 5, 1, 46656, 7776, 1296, 216, 36, 6, 1, 823543, 117649, 16807, 2401, 343, 49, 7, 1, 16777216, 2097152, 262144, 32768, 4096, 512, 64, 8, 1, 387420489, 43046721, 4782969, 531441, 59049, 6561, 729, 81, 9, 1
Offset: 0

Views

Author

Stefano Spezia, Aug 11 2023

Keywords

Examples

			The array begins:
     1,    1,     1,     1,     1,      1, ...
     1,    2,     3,     4,     5,      6, ...
     4,    9,    16,    25,    36,     49, ...
    27,   64,   125,   216,   343,    512, ...
   256,  625,  1296,  2401,  4096,   6561, ...
  3125, 7776, 16807, 32768, 59049, 100000, ...
  ...
		

Crossrefs

Cf. A000012 (n=0), A000169, A000272, A000312 (k=0), A007830 (k=3), A008785 (k=4), A008786 (k=5), A008787 (k=6), A031973 (antidiagonal sums), A052746 (2nd superdiagonal), A052750, A062971 (main diagonal), A079901 (read by descending antidiagonals), A085527 (1st superdiagonal), A085528 (1st subdiagonal), A085532, A099753.

Programs

  • Mathematica
    A[n_,k_]:=(n+k)^n; Join[{1},Table[A[n-k,k],{n,9},{k,0,n}]]//Flatten

Formula

E.g.f. of k-th column: LambertW(-x)^k/(x^k*(1 + LambertW(-x))).
Previous Showing 11-20 of 20 results.