A257808 a(n) = number of nonzero even numbers in range 0 .. n of A233271, the infinite trunk of inverted binary beanstalk.

0, 0, 1, 2, 2, 3, 4, 4, 5, 5, 6, 7, 7, 8, 9, 10, 11, 11, 11, 12, 13, 13, 14, 14, 14, 14, 15, 15, 16, 17, 17, 18, 19, 20, 20, 20, 21, 22, 22, 23, 24, 24, 24, 25, 26, 27, 28, 29, 30, 30, 31, 32, 32, 32, 32, 32, 33, 33, 34, 35, 35, 36, 37, 38, 38, 38, 39, 40, 40, 41, 41, 42, 43, 43, 43, 43, 43, 43, 44, 45, 46, 46, 46, 46, 47, 48, 49, 50, 51

Offset

0,4

Comments

a(n) = the largest number k such that A257804(k) <= n.

Links

Antti Karttunen, Table of n, a(n) for n = 0..16405

Formula

a(0) = 0; for n >= 1, a(n) = (1-A257800(n)) + a(n-1).

Other identities. For all n >= 0:

a(n) = A257806(n) + A257807(n).

a(A257804(n)) = n. [This sequence works as a left inverse for injection A257804.]

Prog

(Scheme, with memoization-macro definec)
(definec (A257808 n) (if (zero? n) n (+ (- 1 (A257800 n)) (A257808 (- n 1)))))

Crossrefs

Cf. A233271, A257800, A257804, A257806, A257807.

Sequence in context: A076935 A019446 A097369 * A249036 A096607 A103416

Adjacent sequences: A257805 A257806 A257807 * A257809 A257810 A257811

Keyword

nonn

Author

Antti Karttunen, May 12 2015

Status

approved