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 1-3 of 3 results.

A065356 Final digits of A065355(n) (in reverse order) for sufficiently large n.

Original entry on oeis.org

6, 8, 6, 9, 5, 0, 9, 7, 5, 9, 7, 0, 1, 7, 4, 3, 6, 6, 7, 5, 5, 3, 4, 4, 7, 4, 9, 0, 6, 9, 4, 9, 8, 6, 0, 4, 6, 7, 6, 5, 9, 1, 5, 0, 0, 2, 9, 8, 8, 7, 3, 1, 6, 2, 5, 1, 3, 1, 2, 5, 0, 2, 5, 2, 5, 7, 7, 0, 9, 9, 5, 6, 6, 9, 4, 3, 4, 1, 3, 4, 9, 9, 7, 3, 3, 4, 8, 4, 0, 2, 1, 1, 8, 3, 7, 9, 7, 1, 8, 7, 8, 6, 2, 3, 8
Offset: 0

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Author

Floor van Lamoen, Oct 31 2001

Keywords

Crossrefs

Programs

  • PARI
    { for (n=0, 1000, f=1; while(f!%10^(n+1)>0, f+=1); x=sum(k=0, f, k!%10^(n+1)); a=(10*(x%10^(n+1)))\10^(n+1); if (n==0, a=3); write("b065356.txt", n, " ", 9 - a) ) } \\ Harry J. Smith, Oct 17 2009

Formula

a(n) = 9-A025016(n), n > 0. - Vladeta Jovovic, Nov 02 2001

Extensions

a(60)-a(104) from Harry J. Smith, Oct 17 2009

A185009 Row sums of A051949 (differences of factorial numbers), seen as a triangle.

Original entry on oeis.org

0, 5, 45, 351, 2847, 25047, 241047, 2534247, 28984167, 358842087, 4785978087, 68453274087, 1045616538087, 16993016806887, 292825130163687, 5333909818803687, 102415654899123687, 2067588695129523687, 43785455761653171687, 970599475776544179687
Offset: 1

Views

Author

Olivier Gérard, Nov 02 2012

Keywords

Crossrefs

cf. A051949.
Other summations of differences of factorials : A206816, A206817, A065355.

Programs

  • Mathematica
    Table[Plus @@ Prepend[Table[(n + 1)! - i!, {i, n, 2, -1}], (n)! - 1], {n, 0, 20}]
  • PARI
    for(n=1,25, print1((n^2-1)*n! - sum(k=1,n-1, k!), ", ")) \\ G. C. Greubel, Jun 09 2017

Formula

a(n)= (n-1)*(n+1)*n! - sum( i!, i=1..n-1)

A343476 Numbers k whose representations in factorial base include each of the digits from 0 to d-1 exactly once, where d = A084558(k) is the number of digits of k in factorial base.

Original entry on oeis.org

0, 2, 10, 13, 14, 46, 67, 68, 77, 82, 85, 86, 238, 355, 356, 461, 466, 469, 470, 503, 526, 547, 548, 557, 562, 565, 566, 1438, 2155, 2156, 2861, 2866, 2869, 2870, 3503, 3526, 3547, 3548, 3557, 3562, 3565, 3566, 3719, 3838, 3955, 3956, 4061, 4066, 4069, 4070, 4103
Offset: 1

Views

Author

Amiram Eldar, Apr 16 2021

Keywords

Comments

The number of terms with k > 1 digits in factorial base is 2^(k-1) - 1 = A000225(k-1).
The number of terms below k!, for k >= 1, is 2^(k-1) - (k-1) = A000325(k-1).

Examples

			2 is a term since its factorial base representation is {1, 0}.
10, 13 and 14 are terms since their factorial base representations are {1, 2, 0}, {2, 0, 1} and {2, 1, 0}, respectively.
		

Crossrefs

A065355 is a subsequence.

Programs

  • Mathematica
    m = 7; bases = Reverse @ Range[2, m]; max = Times @@ bases; factBase[n_] := IntegerDigits[n, MixedRadix[bases]]; q[n_] := Union[(fd = factBase[n])] == Range[0, Length[fd] - 1]; Select[Range[0, max], q]
Showing 1-3 of 3 results.