A236836 The least inverse of A234741: a(n) = the smallest k such that A234741(k) = n, and 0 if no such k exists.

0, 1, 2, 3, 4, 5, 6, 7, 8, 21, 10, 11, 12, 13, 14, 15, 16, 17, 42, 19, 20, 49, 22, 23, 24, 0, 26, 35, 28, 29, 30, 31, 32, 93, 34, 91, 84, 37, 38, 55, 40, 41, 98, 43, 44, 105, 46, 47, 48, 77, 0, 51, 52, 53, 70, 0, 56, 65, 58, 59, 60, 61, 62, 147, 64, 245, 186, 67, 68, 121

Offset

0,3

Comments

A234741(a(n)) = n if n is not in A236834, in which case a(n)=0.

Links

Antti Karttunen, Table of n, a(n) for n = 0..8192

Formula

a(2^n) = 2^n.

a(2n) = 2*a(n).

If n is in A236835, a(n) < A236837(n), otherwise a(n) = A236837(n).

Prog

(Scheme, finding the smallest inverse empirically with a naive loop. A234742 gives an absolute upper bound for any inverse of A234741):
(define (A236836 n) (let ((u (A234742 n))) (let loop ((i 0)) (let ((k (A234741 i))) (cond ((> k u) 0) ((= k n) i) (else (loop (+ i 1))))))))

Crossrefs

A236834 gives the positions of zeros.

Cf. A236833, A236835, A236837 (the greatest inverse of A234741).

Sequence in context: A037343 A366947 A366838 * A134942 A371260 A215888

Adjacent sequences: A236833 A236834 A236835 * A236837 A236838 A236839

Keyword

nonn

Author

Antti Karttunen, Jan 31 2014

Status

approved