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 1-5 of 5 results.

A303991 Row sums of triangle A303990.

Original entry on oeis.org

1, 18, 804, 70980, 10436805, 2303750526, 712510404592, 294018013725192, 156070751204023425, 103597044789173411410, 84072367255899882570876, 81892130447332894817380044, 94289343231845338982163322837, 126676207083751543195799431746150, 196394200592428254386554058525461440
Offset: 1

Views

Author

Wolfdieter Lang, May 22 2018

Keywords

Crossrefs

Programs

  • Mathematica
    Total /@ Table[n^k k^n, {n, 15}, {k, n}] (* Michael De Vlieger, May 24 2018 *)
  • PARI
    a(n) = sum(k=1, n, n^k * k^n); \\ Michel Marcus, May 25 2018

Formula

a(n) = Sum_{k=1..n} A303990(n, k) = Sum_{k=1..n} n^k * k^n, for n >= 1.
a(n) ~ n^(2*n). - Vaclav Kotesovec, Feb 09 2022

A349836 Expansion of Sum_{k>=0} (k * x)^k/(1 - k^2 * x).

Original entry on oeis.org

1, 1, 5, 44, 564, 9665, 211025, 5686104, 184813048, 7118824417, 320295658577, 16626717667348, 985178854556524, 66005199079345025, 4958773228726876257, 414664315430994701616, 38344259607889223269168, 3898112616839310343827009
Offset: 0

Views

Author

Seiichi Manyama, Dec 03 2021

Keywords

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[Sum[k^(2*n - k), {k, 0, n}], {n, 1, 20}]] (* Vaclav Kotesovec, Dec 04 2021 *)
  • PARI
    a(n, t=2) = sum(k=0, n, k^(t*(n-k)+k));
    
  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x)^k/(1-k^2*x)))

Formula

a(n) = Sum_{k=0..n} k^(2*n-k).
a(n) ~ sqrt(Pi) * 2^(1 + 2*n - 2*n/LambertW(2*exp(1)*n)) * (n/LambertW(2*exp(1)*n))^(1/2 + 2*n - 2*n/LambertW(2*exp(1)*n)) / sqrt(1 + LambertW(2*exp(1)*n)). - Vaclav Kotesovec, Dec 04 2021

A368524 a(n) = Sum_{k=1..n} k^2 * n^(n-k).

Original entry on oeis.org

0, 1, 6, 30, 180, 1455, 15666, 213500, 3521736, 68101245, 1508916310, 37661140506, 1045012524348, 31900040161899, 1062139933257690, 38299757176168440, 1486670929792295696, 61800664096000744569, 2738952078516469743678, 128909373997071187219990
Offset: 0

Views

Author

Seiichi Manyama, Dec 28 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=1, n, k^2*n^(n-k));

Formula

a(n) = [x^n] x * (1+x)/((1-n*x) * (1-x)^3).
a(n) = n * (n+1) * (n^n - n^2 + n - 1)/(n-1)^3 for n > 1.

A368525 a(n) = Sum_{k=1..n} k^3 * n^(n-k).

Original entry on oeis.org

0, 1, 10, 60, 364, 2745, 27246, 346864, 5422264, 100449225, 2149062490, 52097910876, 1410401518692, 42153624499441, 1378058477508454, 48900582823143360, 1871456346915007216, 76821658841556480753, 3366451935514051046802, 156839738363103277783900
Offset: 0

Views

Author

Seiichi Manyama, Dec 28 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=1, n, k^3*n^(n-k));

Formula

a(n) = [x^n] x * (1+4*x+x^2)/((1-n*x) * (1-x)^4).
a(n) = n * (n^n * (n^2 + 4*n + 1) - n^5 - 3*n^2 - n - 1)/(n-1)^4 for n > 1.

A368504 Square array T(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where T(n,k) = Sum_{j=0..n} k^(n-j) * j^k.

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 3, 1, 0, 1, 6, 6, 1, 0, 1, 11, 21, 10, 1, 0, 1, 20, 60, 58, 15, 1, 0, 1, 37, 161, 244, 141, 21, 1, 0, 1, 70, 428, 900, 857, 318, 28, 1, 0, 1, 135, 1149, 3164, 4225, 2787, 685, 36, 1, 0, 1, 264, 3132, 10990, 18945, 18196, 8704, 1434, 45, 1
Offset: 0

Views

Author

Seiichi Manyama, Dec 27 2023

Keywords

Examples

			Square array begins:
  1,  0,   0,    0,     0,      0,      0, ...
  1,  1,   1,    1,     1,      1,      1, ...
  1,  3,   6,   11,    20,     37,     70, ...
  1,  6,  21,   60,   161,    428,   1149, ...
  1, 10,  58,  244,   900,   3164,  10990, ...
  1, 15, 141,  857,  4225,  18945,  81565, ...
  1, 21, 318, 2787, 18196, 102501, 536046, ...
		

Crossrefs

Columns k=0..5 give A000012, A000217, A047520, A066999, A067534, A218376.
Main diagonal gives A368505.
Cf. A368486.

Programs

  • PARI
    T(n, k) = sum(j=0, n, k^(n-j)*j^k);

Formula

G.f. of column k: x*A_k(x)/((1-k*x) * (1-x)^(k+1)), where A_n(x) are the Eulerian polynomials for k > 0.
T(0,k) = 0^k; T(n,k) = k*T(n-1,k) + n^k.
Showing 1-5 of 5 results.