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.

A231664 a(n) = Sum_{i=0..n} digsum_4(i), where digsum_4(i) = A053737(i).

Original entry on oeis.org

0, 1, 3, 6, 7, 9, 12, 16, 18, 21, 25, 30, 33, 37, 42, 48, 49, 51, 54, 58, 60, 63, 67, 72, 75, 79, 84, 90, 94, 99, 105, 112, 114, 117, 121, 126, 129, 133, 138, 144, 148, 153, 159, 166, 171, 177, 184, 192, 195, 199, 204, 210, 214, 219, 225, 232, 237, 243, 250, 258, 264, 271, 279, 288, 289, 291, 294, 298, 300, 303, 307, 312, 315, 319, 324, 330, 334, 339, 345, 352, 354, 357
Offset: 0

Views

Author

N. J. A. Sloane, Nov 13 2013

Keywords

References

  • Jean-Paul Allouche and Jeffrey Shallit, Automatic sequences, Cambridge University Press, 2003, p. 94.

Crossrefs

Programs

  • Magma
    [(&+[&+Intseq(j, 4): j in [0..n]]): n in [0..100]]; // G. C. Greubel, Feb 16 2019
  • Maple
    ListTools:-PartialSums([seq(convert(convert(n,base,4),`+`), n=0..200)]); # Robert Israel, Sep 20 2017
  • Mathematica
    Table[Sum[Total[IntegerDigits[j, 4]], {j,0,n}], {n, 0, 100}] (* G. C. Greubel, Feb 16 2019 *)
  • PARI
    a(n) = sum(i=0, n, sumdigits(i, 4)); \\ Michel Marcus, Sep 20 2017
    

Formula

G.f.: g(x) satisfies g(x) = (1+x+x^2+x^3)^2*g(x^4) + (x+2*x^2+3*x^3)/(1-x-x^4+x^5). - Robert Israel, Sep 20 2017
a(n) ~ 3*n*log(n)/(4*log(2)). - Amiram Eldar, Dec 09 2021