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 A219643 #10 Nov 25 2012 23:48:26 %S A219643 0,1,2,3,5,7,8,10,13,15,18,21,23,26,29,32,34,36,39,42,45,47,50,54,55, %T A219643 57,60,63,66,68,71,75,78,81,84,89,91,94,97,100,102,105,109,112,115, %U A219643 118,123,126,130,134,138,143,144,146,149,152,155,157,160,164,167 %N A219643 Least inverse of A219642; a(n) = minimal i such that A219642(i) = n. %H A219643 A. Karttunen, <a href="/A219643/b219643.txt">Table of n, a(n) for n = 0..10000</a> %o A219643 (Scheme with _Antti Karttunen_'s Intseq-library, three different variants): %o A219643 (define A219643 (MATCHING-POS 0 0 (lambda (i) (or (< i 1) (not (= (A219642 (- i 1)) (A219642 i))))))) %o A219643 (define A219643v2 (LEAST-I-WITH-FUN-I-EQ-N 0 0 A219642)) ;; Slow! %o A219643 (define A219643v3 (RECORD-POS 0 0 A219642)) %Y A219643 Cf. A219645 for the greatest inverse. A219644 gives the first differences. %Y A219643 This sequence is based on Fibonacci number system (Zeckendorf expansion): A014417. For analogous sequence in binary system, see: A213708, for factorial number system: A219653. %K A219643 nonn %O A219643 0,3 %A A219643 _Antti Karttunen_, Nov 24 2012