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 A154470 #9 Jan 28 2025 13:40:06 %S A154470 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25, %T A154470 26,27,28,32,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48, %U A154470 49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,74 %N A154470 Rewriting function for Wolfram's e[x_][y_] -> x[x[y]] symbolic system transformation, implemented on nihilistic S-expressions (parenthesizations) encoded by A014486. %C A154470 Here we use the empty list () as a marker for symbol 'e'. Any sublist like (... ()(x1 x2 ... xn)(y1 y2 ... yn) ...) is transformed into the form (... x1 x2 ... xn (x1 x2 ... xn (y1 y2 ... yn)) ...). A054471 gives the iterations of this function, starting from initial value 31706. %H A154470 Antti Karttunen, <a href="/A154470/b154470.txt">Table of n, a(n) for n = 0..2055</a> %H A154470 Stephen Wolfram, <a href="http://www.wolframscience.com/nksonline/page-102">A New Kind of Science, Wolfram Media Inc., (2002), pp. 102</a>--104, 896-898. %o A154470 (Scheme) (define (*A154470 s) (cond ((null? s) s) ((and (null? (car s)) (>= (length s) 3) (pair? (second s)) (pair? (third s))) (append (second s) (cons (append (second s) (list (third s))) (*A154470 (cdddr s))))) (else (cons (*A154470 (car s)) (*A154470 (cdr s)))))) %Y A154470 Cf. A014486. %Y A154470 Differs from A001477 for the first time at n=29, where a(n)=32. %K A154470 nonn %O A154470 0,3 %A A154470 _Antti Karttunen_, Jan 11 2009