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 1-2 of 2 results.

A095703 Integer part of the (positive) solution to x^x = 10^n.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 7, 8, 9, 10, 10, 11, 12, 12, 13, 13, 14, 15, 15, 16, 17, 17, 18, 18, 19, 19, 20, 21, 21, 22, 22, 23, 23, 24, 25, 25, 26, 26, 27, 27, 28, 28, 29, 29, 30, 30, 31, 31, 32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 37, 37, 38, 38, 39, 39, 40, 40, 41, 41
Offset: 0

Views

Author

Cino Hilliard, Jul 06 2004

Keywords

Crossrefs

Programs

  • Maple
    a:= n-> `if`(n=0, 1, (t-> floor(t/LambertW(t)))(n*log(10))):
    seq(a(n), n=0..80);  # Alois P. Heinz, Nov 07 2019
  • PARI
    a(n) = floor(solve(x=1, max(10,n+1), x^x-10^n))
    
  • PARI
    a(n) = {my(k=1); while(k^k <= 10^n, k++); k-1} \\ Andrew Howroyd, Nov 07 2019

Formula

a(n) = n*log(10)/LambertW(n*log(10)) for n > 0, a(0) = 1. - Alois P. Heinz, Nov 07 2019

Extensions

Terms a(23) and beyond from Andrew Howroyd, Nov 07 2019

A328325 Expansion of Product_{k>=0} 1/(1 - x^(k^k)).

Original entry on oeis.org

1, 2, 3, 4, 6, 8, 10, 12, 15, 18, 21, 24, 28, 32, 36, 40, 45, 50, 55, 60, 66, 72, 78, 84, 91, 98, 105, 113, 122, 131, 140, 150, 161, 172, 183, 195, 208, 221, 234, 248, 263, 278, 293, 309, 326, 343, 360, 378, 397, 416, 435, 455, 476, 497, 519, 542, 566, 590, 615, 641, 668, 695
Offset: 0

Views

Author

Seiichi Manyama, Oct 12 2019

Keywords

Comments

Partial sums of A328301.

Examples

			G.f.: 1/(1-x) + x/(1-x)^2 + x^4/((1-x)^2*(1-x^4)) + x^27/((1-x)^2*(1-x^4)*(1-x^27)) + ... .
		

Crossrefs

Programs

  • Maple
    b:= proc(n, i) option remember; `if`(n=0 or i=1, 1,
          b(n, i-1)+(p-> `if`(p>n, 0, b(n-p, i)))(i^i))
        end:
    a:= proc(n) option remember; `if`(n<2, n+1, a(n-1)+
          b(n, floor((t-> t/LambertW(t))(log(n)))))
        end:
    seq(a(n), n=0..100);  # Alois P. Heinz, Oct 12 2019
  • Mathematica
    b[n_, i_] := b[n, i] = If[n == 0 || i == 1, 1, b[n, i-1] + With[{p = i^i}, If[p > n, 0, b[n-p, i]]]];
    a[n_] := a[n] = If[n < 2, n+1, a[n-1] + b[n, Floor[PowerExpand[Log[n]/ ProductLog[Log[n]]]]]];
    Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Sep 14 2022, after Alois P. Heinz *)
  • PARI
    N=99; x='x+O('x^N); m=1; while(N>=m^m, m++); Vec(1/prod(k=0, m-1, 1-x^k^k))

Formula

a(n) = Sum_{k=0..n} A328301(k).
G.f.: 1/(1-x) + Sum_{n>0} x^(n^n) / Product_{k=0..n} (1 - x^(k^k)).
Showing 1-2 of 2 results.