login
A257804
Positions of even numbers in A233271, the infinite trunk of inverted binary beanstalk.
10
0, 2, 3, 5, 6, 8, 10, 11, 13, 14, 15, 16, 19, 20, 22, 26, 28, 29, 31, 32, 33, 36, 37, 39, 40, 43, 44, 45, 46, 47, 48, 50, 51, 56, 58, 59, 61, 62, 63, 66, 67, 69, 71, 72, 78, 79, 80, 84, 85, 86, 87, 88, 89, 91, 92, 94, 97, 98, 99, 100, 101, 102, 104, 105, 110, 112, 113, 115, 116, 117, 120, 121, 123, 124, 125, 126, 129, 130
OFFSET
0,2
COMMENTS
We start indexing of this sequence from 0, because a(0) = 0 is a special case, which can be conveniently ignored by considering only the terms from a(1) onward.
LINKS
FORMULA
Other identities. For all n >= 0:
A257808(a(n)) = n. [A257808 works as a left inverse for this injective function.]
PROG
(Scheme, with Antti Karttunen's IntSeq-library)
(define A257804 (MATCHING-POS 0 0 (lambda (n) (even? (A233271 n)))))
(define A257804 (MATCHING-POS 0 0 (lambda (n) (even? (A257800 n)))))
CROSSREFS
Complement: A257803.
Sequence in context: A233592 A320773 A138390 * A285209 A184590 A047448
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 12 2015
STATUS
approved