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.

A324888 Minimal number of primorials (A002110) that add to A108951(n).

Original entry on oeis.org

1, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 4, 1, 2, 6, 4, 1, 4, 1, 4, 6, 2, 1, 4, 6, 2, 2, 4, 1, 6, 1, 2, 6, 2, 10, 8, 1, 2, 6, 2, 1, 2, 1, 4, 6, 2, 1, 4, 8, 12, 6, 4, 1, 4, 6, 8, 6, 2, 1, 6, 1, 2, 6, 4, 14, 12, 1, 4, 6, 10, 1, 6, 1, 2, 10, 4, 18, 12, 1, 4, 8, 2, 1, 4, 12, 2, 6, 8, 1, 12, 18, 4, 6, 2, 8, 8, 1, 16, 12, 8, 1, 12, 1, 8, 8
Offset: 1

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Author

Antti Karttunen, Mar 30 2019

Keywords

Comments

Sum of digits when A108951(n) is written in primorial base (A049345).

Crossrefs

Cf. A324383, A324386, A324387 (permutations of this sequence).

Programs

  • Mathematica
    With[{b = Reverse@ Prime@ Range@ 120}, Array[Total@ IntegerDigits[#, MixedRadix[b]] &@ Apply[Times, Map[#1^#2 & @@ # &, FactorInteger[#] /. {p_, e_} /; e > 0 :> {Times @@ Prime@ Range@ PrimePi@ p, e}]] &, 105] ] (* Michael De Vlieger, Nov 18 2019 *)
  • PARI
    A034386(n) = prod(i=1, primepi(n), prime(i));
    A108951(n) = { my(f=factor(n)); prod(i=1, #f~, A034386(f[i, 1])^f[i, 2]) };  \\ From A108951
    A276150(n) = { my(s=0,m); forprime(p=2, , if(!n, return(s)); m = n%p; s += m; n = (n-m)/p); };
    A324888(n) = A276150(A108951(n));

Formula

a(n) = A276150(A108951(n)).
a(n) = A001222(A324886(n)).