

A154470


Rewriting function for Wolfram's e[x_][y_] > x[x[y]] symbolic system transformation, implemented on nihilistic Sexpressions (parenthesizations) encoded by A014486.


2



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, 26, 27, 28, 32, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 74
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

0,3


COMMENTS

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.


LINKS

A. Karttunen, Table of n, a(n) for n = 0..2055
S. Wolfram, A New Kind of Science, Wolfram Media Inc., (2002), pp. 102104, 896898.


PROG

(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))))))


CROSSREFS

Differs from A001477 for the first time at n=29, where a(n)=32.
Sequence in context: A246099 A280865 A124231 * A194907 A090106 A167662
Adjacent sequences: A154467 A154468 A154469 * A154471 A154472 A154473


KEYWORD

nonn


AUTHOR

Antti Karttunen, Jan 11 2009


STATUS

approved



