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.

A217757 Product_{i=0..n} (i! + 1).

Original entry on oeis.org

2, 4, 12, 84, 2100, 254100, 183206100, 923541950100, 37238134969982100, 13513011656042074430100, 49036030210457135734021310100, 1957361459740805606124917565020990100, 937579272951542930363610919638075856505150100
Offset: 0

Views

Author

Jon Perry, Mar 23 2013

Keywords

Crossrefs

Programs

  • JavaScript
    function factorial(n) {
    var i,c=1;
    for (i=2;i<=n;i++) c*=i;
    return c;
    }
    a=2;
    for (j=1;j<10;j++) {
    a*=(factorial(j)+1);
    document.write(a+", ");
    }
  • Maple
    a:= proc(n) a(n):= `if`(n=0, 2, a(n-1)*(n!+1)) end:
    seq(a(n), n=0..14);  # Alois P. Heinz, May 20 2013
  • Mathematica
    Table[Product[i!+1,{i,0,n}],{n,0,12}]  (* Geoffrey Critzer, May 04 2013 *)
    Rest[FoldList[Times,1,Range[0,15]!+1]] (* Harvey P. Dale, May 28 2013 *)

Formula

a(n) ~ c * A000178(n), where c = A238695 = Product_{k>=0} (1 + 1/k!) = 7.364308272367257256372772509631... . - Vaclav Kotesovec, Jul 20 2015

A260231 a(n) = Product_{k=1..n} (1 + k^k).

Original entry on oeis.org

2, 10, 280, 71960, 224946960, 10495350312720, 8643382777938679680, 145011908479540041684850560, 56180584638978557924165229531974400, 561805846445966163880630853243909229531974400, 160289764609087349005207761687490741791453382934816332800
Offset: 1

Views

Author

Vaclav Kotesovec, Jul 20 2015

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Product[1+k^k,{k,1,n}],{n,1,12}]
    FoldList[Times,Table[1+k^k,{k,12}]] (* Harvey P. Dale, Jul 19 2025 *)

Formula

a(n) ~ c * A002109(n), where c = Product_{k>=1} (1 + 1/k^k) = 2.60361190459951423330221282635022049352582879064202503882732200701325334...
Showing 1-2 of 2 results.