This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A129603 #6 Dec 14 2023 14:42:05 %S A129603 0,1,2,7,8,5,14,31,32,17,10,23,56,29,62,127,128,65,34,71,40,21,46,95, %T A129603 224,113,58,119,248,125,254,511,512,257,130,263,136,69,142,287,160,81, %U A129603 42,87,184,93,190,383,896,449,226,455,232,117,238,479,992,497,250,503 %N 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). %e A129603 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. %o A129603 (MIT/GNU Scheme) %o A129603 ;;; binexp->runcount1list and runcount1list->binexp given in A129594. %o A129603 (define (A129603 n) (runcount1list->binexp (map (lambda (i) (- (* 2 i) 1)) (binexp->runcount1list n)))) %Y A129603 Cf. A001196, A129602. %K A129603 nonn,base %O A129603 0,3 %A A129603 _Antti Karttunen_, May 01 2007