A361643 The binary expansion of a(n) specifies which primes divide A359804(n).

0, 1, 2, 4, 1, 3, 5, 8, 2, 1, 6, 9, 16, 3, 5, 10, 17, 4, 3, 9, 7, 18, 12, 1, 3, 5, 11, 17, 6, 8, 33, 2, 5, 9, 3, 20, 10, 1, 7, 13, 19, 32, 36, 65, 34, 6, 129, 24, 3, 5, 11, 17, 68, 66, 257, 7, 40, 18, 33, 132, 3, 9, 5, 130, 14, 513, 21, 258, 9, 260, 3, 72, 7

Offset: 1

Author

Rémy Sigrist, Mar 19 2023

Keywords

• nonn
• base

Examples

			The first terms, in decimal and in binary, alongside A359804(n) and its divisibility by small prime numbers, are:
  n   a(n)  bin(a(n))  A359804(n)  Divisibility by:
                                      7  5  3  2
  --  ----  ---------  ----------     -  -  -  -
   1     0          0           1
   2     1          1           2              X
   3     2         10           3           X
   4     4        100           5        X
   5     1          1           4              X
   6     3         11           6           X  X
   7     5        101          10        X     X
   8     8       1000           7     X
   9     2         10           9           X
  10     1          1           8              X
		

Links

• Rémy Sigrist, Table of n, a(n) for n = 1..10000
• Rémy Sigrist, PARI program

Crossrefs

Cf. A087207, A359804.

Programs

PARI

See Links section.

Formula

a(n) = A087207(A359804(n)).