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.

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A385058 E.g.f. A(x) satisfies A(x) = exp(x*A(x)/A(-x*A(x))).

Original entry on oeis.org

1, 1, 5, 31, 333, 3841, 57463, 836109, 11138921, 14908465, -10091931669, -687827361011, -40151825312387, -2071761364164231, -106488772704576961, -5002145237145820979, -203989286928198178863, -4164191357488024315679, 500440079223957671460307, 99906607739361143393212941
Offset: 0

Views

Author

Seiichi Manyama, Jun 16 2025

Keywords

Crossrefs

Column k=1 of A385061.

Programs

  • PARI
    a(n, k=-1) = if(n*k==0, 0^n, (-1)^n*k*sum(j=1, n, (-n+k)^(j-1)*binomial(n, j)*a(n-j, j)));

Formula

See A385061.

A181320 Triangle T(n,m) read by rows: the number of series-parallel networks with n+2 vertices and m+n+1 edges.

Original entry on oeis.org

1, 1, 1, 2, 7, 5, 6, 48, 91, 49, 24, 360, 1304, 1697, 729, 120, 3000, 17910, 41440, 41051, 14641, 720, 27720, 249900, 899730, 1524282, 1218745, 371293
Offset: 0

Views

Author

R. J. Mathar, Jan 26 2011

Keywords

Comments

Obtained by evaluating the half-exponential generating function D(x,y) in Lemma 3.1 of Drmota et al.
D(x,y) = sum_{n,m} d_(n,m)*x^n*y^m/n! with log( (1+D)/(1+y)) = x*D^2/(1+x*D).
The diagonal appears to be A052750.

Examples

			The table d_(n,m) [which is T(n,m) with leading zeros maintained] for the number of SP networks with n+2 vertices and m nodes (internal nodes labeled from 1 to n) starts in row n=0 with columns m>=0 as:
n\m| 0  1  2  3  4
----------------------
0  | 0  1
1  | 0  0  1  1
2  | 0  0  0  2  7  5
3  | 0  0  0  0  6 48  91  49
		

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 21-23 of 23 results.