login
A129603
Replace in the binary expansion of n each run of k 0's (or 1's) with 2k-1 0's (or 1's).
2
0, 1, 2, 7, 8, 5, 14, 31, 32, 17, 10, 23, 56, 29, 62, 127, 128, 65, 34, 71, 40, 21, 46, 95, 224, 113, 58, 119, 248, 125, 254, 511, 512, 257, 130, 263, 136, 69, 142, 287, 160, 81, 42, 87, 184, 93, 190, 383, 896, 449, 226, 455, 232, 117, 238, 479, 992, 497, 250, 503
OFFSET
0,3
EXAMPLE
a(1) = 1, as 1 is 1 in binary and single runs stay intact (as 2*1 - 1 = 1). a(9) = 17, as 9 is 1001 in binary and keeping the most and the least significant runs as '1' and changing the center run '00' to '000', we get 10001 in binary, 17 in decimal.
PROG
(MIT/GNU Scheme)
;;; binexp->runcount1list and runcount1list->binexp given in A129594.
(define (A129603 n) (runcount1list->binexp (map (lambda (i) (- (* 2 i) 1)) (binexp->runcount1list n))))
CROSSREFS
Sequence in context: A021363 A352495 A141721 * A263809 A102268 A155062
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, May 01 2007
STATUS
approved