A228087 a(n) = largest k which satisfies n = k + bitcount(k), or 0 if no such k exists. Here bitcount(k) (A000120) gives the number of 1's in binary representation of nonnegative integer k.

0, 0, 1, 2, 0, 4, 0, 5, 6, 8, 7, 9, 10, 0, 12, 0, 13, 16, 0, 17, 18, 0, 20, 0, 21, 22, 24, 23, 25, 26, 0, 28, 0, 32, 30, 33, 34, 0, 36, 0, 37, 38, 40, 39, 41, 42, 0, 44, 0, 45, 48, 0, 49, 50, 0, 52, 0, 53, 54, 56, 55, 57, 58, 0, 60, 64, 61, 65, 66, 63, 68, 0

Offset

0,4

Comments

A083058(n)+1 gives a lower bound for nonzero terms, n-1 an upper bound.

Links

Antti Karttunen, Table of n, a(n) for n = 0..8192

Index entries for Colombian or self numbers and related sequences

Prog

(Scheme) (define (A228087 n) (let loop ((k n)) (cond ((<= k (A083058 n)) 0) ((= n (A092391 k)) k) (else (loop (- k 1))))))

Crossrefs

Cf. A228086, A228085. A010061 gives the positions of zeros after a(0). The union of A010061 and A228088 gives the positions where a(n) = A228086(n).

Cf. also A213724, A227643.

Sequence in context: A225437 A065806 A331185 * A320582 A119690 A166260

Adjacent sequences: A228084 A228085 A228086 * A228088 A228089 A228090

Keyword

nonn

Author

Antti Karttunen, Aug 09 2013

Status

approved