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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 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified December 6 16:24 EST 2019. Contains 329808 sequences. (Running on oeis4.)