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A257808
a(n) = number of nonzero even numbers in range 0 .. n of A233271, the infinite trunk of inverted binary beanstalk.
9
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
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
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 12 2015
STATUS
approved