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.

A014838 Sum of all the digits of n in every prime base from 2 to n-1.

Original entry on oeis.org

2, 3, 5, 6, 9, 11, 11, 10, 14, 16, 21, 21, 21, 23, 29, 32, 39, 42, 42, 39, 47, 52, 53, 49, 52, 53, 62, 66, 76, 83, 82, 76, 77, 82, 93, 87, 85, 90, 102, 107, 120, 123, 129, 120, 134, 144, 147, 153, 150, 151, 166, 176, 178, 185, 181, 168, 184, 194, 211, 199, 207
Offset: 3

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Programs

  • Mathematica
    Table[Sum[If[PrimeQ[i], Mod[Total[IntegerDigits[n, i]], n], 0], {i, 2, n-1}],{n, 3, 63}] (* Stefano Spezia, Sep 06 2022 *)
  • PARI
    a(n) = {s = 0; forprime (i=2, n-1, d = digits(n, i); s += sum(j=1, #d, d[j]);); s;} \\ Michel Marcus, May 30 2014
    
  • Python
    from sympy.ntheory import digits, isprime
    def a(n): return sum(sum(digits(n, b)[1:]) for b in range(2, n) if isprime(b))
    print([a(n) for n in range(3, 64)]) # Michael S. Branicky, Sep 06 2022