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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A356365 For any nonnegative integer n with binary expansion Sum_{k = 1..w} 2^e_k, let m be the least integer such that the values e_k mod m are all distinct; a(n) = Sum_{k = 1..w} 2^(e_k mod m).

Original entry on oeis.org

0, 1, 1, 3, 1, 5, 3, 7, 1, 3, 3, 11, 3, 13, 7, 15, 1, 3, 3, 19, 6, 7, 7, 23, 3, 25, 11, 27, 7, 29, 15, 31, 1, 3, 6, 7, 3, 7, 7, 39, 5, 11, 7, 43, 14, 15, 15, 47, 3, 7, 19, 51, 7, 53, 23, 55, 7, 57, 27, 59, 15, 61, 31, 63, 1, 5, 3, 7, 5, 7, 7, 71, 3, 13, 14, 15
Offset: 0

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Author

Rémy Sigrist, Oct 16 2022

Keywords

Comments

See A293390 for the corresponding m's.

Examples

			The first terms, alongside their binary expansions and the corresponding m's, are:
  n    a(n)  bin(n)   bin(a(n))  m
  ---  ----  -------  ---------  -
    0     0        0          0  0
    1     1        1          1  1
    2     1       10          1  1
    3     3       11         11  2
    4     1      100          1  1
    5     5      101        101  3
    6     3      110         11  2
    7     7      111        111  3
    8     1     1000          1  1
    9     3     1001         11  2
   10     3     1010         11  3
   11    11     1011       1011  4
   12     3     1100         11  2
   13    13     1101       1101  4
   14     7     1110        111  3
   15    15     1111       1111  4
   16     1    10000          1  1
		

Crossrefs

Programs

  • PARI
    a(n) = { my (b=vector(hammingweight(n))); for (i=1, #b, n-=2^b[i]=valuation(n,2);); for (m=1, oo, if (#Set(b%m)==#b, b%=m; break;);); sum(i=1, #b, 2^b[i]); }

Formula

A000120(a(n)) = A000120(n).
a(n) = 1 iff n is a power of 2.
a(2^k - 1) = 2^k - 1 for any k >= 0.
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