OFFSET
1,1
COMMENTS
There are 11 forty-two-digit terms in the sequence. Further terms are obtained (a) by inserting at the center of these terms either any number of 0's (for 166425621223026859056339052269787863565428, 311906350108036145286307567270199935391877, 466287189883036620417374974360601118217236, 658139747564935391877311906350534262959233, 703288139752915027377325180481642968027593) or any number of 9's (for the other six terms) and (b) by concatenating a term any number of times with itself and inserting an equal number of 0's at all junctures. Method (b) may be applied recursively to all terms. - Clarified by Ray Chandler, Oct 14 2017.
LINKS
Ray Chandler, Table of n, a(n) for n = 1..11
J. H. E. Cohn, Palindromic differences, Fibonacci Quart. 28 (1990), no. 2, 113-120.
FORMULA
n = f^11(n), n <> f^k(n) for k < 11, where f: x -> |x - reverse(x)|.
EXAMPLE
166425621223026859056339052269787863565428 -> 658139747564935391877311906350534262959233 -> 325180485129881782763533712811068515027377 -> 448540030730236434571833574377853069054146 -> 192910929628537040766341860254183960991698 -> 703288139752915027377325180481642968027593 -> 307567270506730945853551459962385036145286 -> 374974360076539008301807089075220036620417 -> 339052269946031972406296711860450026859056 -> 311906350108036145286307567270199935391877 -> 466287189883036620417374974360601118217236 -> 166425621223026859056339052269787863565428.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Meritxell Vila Miñana, Sep 24 2017
EXTENSIONS
Terms corrected by Ray Chandler, Sep 27 2017
STATUS
approved