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A317419
a(n) = number of k with 1 <= k <= n-1 such that a(k) AND a(n-k) = 0 (where AND denotes the bitwise AND operator).
2
0, 1, 2, 2, 4, 4, 4, 6, 8, 8, 6, 6, 8, 8, 8, 10, 12, 12, 10, 14, 20, 14, 8, 10, 12, 12, 8, 8, 12, 14, 14, 10, 10, 12, 12, 8, 10, 14, 16, 12, 6, 10, 12, 14, 8, 8, 12, 14, 14, 14, 14, 10, 12, 12, 8, 12, 18, 16, 12, 8, 10, 14, 18, 14, 10, 18, 18, 16, 12, 14, 18
OFFSET
1,3
COMMENTS
All terms are even except a(2) = 1.
See A317420 for similar sequences.
LINKS
EXAMPLE
For n = 4:
- a(1) AND a(3) = 0 AND 2 = 0,
- a(2) AND a(2) = 1 AND 1 = 1 <> 0,
- a(3) AND a(1) = 2 AND 0 = 0,
- hence a(4) = 2.
PROG
(PARI) a = vector(71); for (n=1, #a, a[n] = sum(k=1, n-1, bitand(a[k], a[n-k])==0); print1 (a[n] ", "))
CROSSREFS
Cf. A317420.
Sequence in context: A333787 A062570 A108514 * A364843 A372678 A120456
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Jul 27 2018
STATUS
approved