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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A216377 The most significant digit in base n representation of n!.

Original entry on oeis.org

1, 2, 1, 4, 3, 2, 1, 6, 3, 2, 1, 7, 4, 2, 1, 10, 5, 2, 1, 15, 8, 4, 2, 1, 13, 6, 3, 1, 25, 12, 6, 3, 1, 25, 12, 6, 3, 1, 28, 13, 6, 3, 1, 33, 16, 7, 3, 1, 41, 20, 9, 4, 2, 1, 26, 12, 6, 2, 1, 38, 18, 8, 3, 1, 57, 27, 12, 5, 2, 1, 43, 20, 9, 4, 2, 72, 33, 15, 7, 3, 1
Offset: 2

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Author

Alex Ratushnyak, Sep 06 2012

Keywords

Comments

a(n) < n, by definition.
Numbers n such that a(n)=1: 2, 4, 8, 12, 16, 20, 25, 29, 34, 39, 44, 49, 55, 60, 65, 71, 82, 88, 94, 105, 111, 117, 123, 136, ... (see A221707).
Numbers n such that a(n) > a(k) for k < n: 2, 3, 5, 9, 13, 17, 21, 30, 40, 45, 50, 66, 77, 100, 118, 124, 130, 155, 161, 226, 246, 273, 371, 378, 385, 421, 450, 472, 509, 584, 599, 637, 660, 683, 745, 784, 855, 983, 991, 999, ... (see A221708).

Crossrefs

Cf. also to scatter plots of A265891 and A265894.

Programs

  • Maple
    a:= n-> iquo(n!, n^ilog[n](n!)):
    seq(a(n), n=2..100);  # Alois P. Heinz, Sep 06 2012
  • Mathematica
    Table[IntegerDigits[n!, n][[1]], {n, 2, 100}] (* T. D. Noe, Sep 06 2012 *)
  • Python
    import math
    def modlg(a,b):
        return a // b**int(math.log(a,b))
    for n in range(2,88):
        print(modlg(math.factorial(n), n), end=', ')

Formula

a(n) = modlg(n!, n), where modlg is the function defined in A215894: modlg(A,B) = floor(A / B^floor(logB(A))), logB is the logarithm base B.

A221708 Records in A216377.

Original entry on oeis.org

2, 3, 5, 9, 13, 17, 21, 30, 40, 45, 50, 66, 77, 100, 118, 124, 130, 155, 161, 226, 246, 273, 371, 378, 385, 421, 450, 472, 509, 584, 599, 637, 660, 683, 745, 784, 855, 983, 991, 999, 1072, 1121, 1162, 1228, 1378, 1420, 1479, 1598, 1615, 1761
Offset: 1

Views

Author

N. J. A. Sloane, Jan 25 2013

Keywords

Crossrefs

Programs

  • Mathematica
    r=0; n=f=2; Table[While[(k = Floor[f/n^Floor@Log[n,f]]) <= r, f *= ++n]; r = k; n, {50}] (* Giovanni Resta, Jan 28 2013 *)

Extensions

a(41)-a(50) from Giovanni Resta, Jan 28 2013
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