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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

Paul Tek, Illustration of how natural numbers in range 0 .. 133 are organized as a binary tree in the binary beanstalk

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.)