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 A257508 Next-to-leaf vertices in binary beanstalk; Numbers n for which A257265(n) = 1. 7
 1, 3, 4, 7, 10, 11, 15, 18, 22, 23, 25, 26, 31, 34, 38, 39, 41, 46, 47, 49, 50, 54, 56, 57, 63, 66, 70, 71, 73, 78, 79, 81, 82, 86, 88, 94, 95, 97, 98, 102, 104, 105, 110, 113, 116, 117, 119, 120, 127, 130, 134, 135, 137, 142, 143, 145, 146, 150, 152, 158, 159, 161, 162, 166, 168, 169, 174, 177, 180, 181 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Numbers n for which A257265(n) = 1, in other words, numbers n for which a descendant leaf nearest to n in binary beanstalk is one edge away. Numbers n such that either A079559(A213723(n)) or A079559(A213724(n)) (or both) are zero. Equal to A257507 with duplicate terms removed. LINKS Antti Karttunen, Table of n, a(n) for n = 1..12289 EXAMPLE 3 is present because it has an immediate leaf-child 5, as A011371(5) = 3. 4 is present because it has an immediate leaf-child 6, as A011371(6) = 4. 10 is present because it has two immediate leaf-children, 12 and 13, as A011371(12) = A011371(13) = 10. See also Paul Tek's illustration. PROG (Scheme, with Antti Karttunen's IntSeq-library, two alternatives) (define A257508 (MATCHING-POS 1 0 (lambda (n) (= 1 (A257265 n))))) (define A257508 (MATCHING-POS 1 0 (lambda (n) (or (zero? (A079559 (A213723 n))) (zero? (A079559 (A213724 n))))))) ;; Compare to the definition of A257512. (Haskell) a257508 n = a257508_list !! (n-1) a257508_list = filter ((== 1) . a257265) [0..] -- Reinhard Zumkeller, May 06 2015 CROSSREFS Positions of 1's in A257265. Subsequence of A005187. Cf. A011371, A079559, A213723, A213724, A257507, A257509, A257512 (a subsequence). Sequence in context: A047342 A334469 A228854 * A221975 A340603 A137294 Adjacent sequences:  A257505 A257506 A257507 * A257509 A257510 A257511 KEYWORD nonn AUTHOR Antti Karttunen, May 03 2015 STATUS approved

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Last modified June 18 11:39 EDT 2021. Contains 345098 sequences. (Running on oeis4.)