OFFSET
1,1
COMMENTS
There are 9 forty-eight-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 111603518721165960373027269626940447783074704878, 176512193475025275151977319848516480415708873428, 637711546692957642526533655473763239712353991164, 647866614039059340696936459303056040158682342243, 766803951666578089253935450746129113344740601233) or any number of 9's (for the other four 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..9
J. H. E. Cohn, Palindromic differences, Fibonacci Quart. 28 (1990), no. 2, 113-120.
FORMULA
n = f^9(n), n <> f^k(n) for k < 9, where f: x -> |x - reverse(x)|.
EXAMPLE
111603518721165960373027269626940447783074704878 -> 766803951666578089253935450746129113344740601233 -> 434697904223266167606880911393148237678581292566 -> 230594281653466673786238177213613424643828503868 -> 637711546692957642526533655473763239712353991164 -> 176512193475025275151977319848516480415708873428 -> 647866614039059340696936459303056040158682342243 -> 305623327188018690392981819607012089228265673497 -> 488753235634961520313936369686084721653457653006 -> 111603518721165960373027269626940447783074704878
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Meritxell Vila Miñana, Sep 25 2017
EXTENSIONS
Terms ordered by Ray Chandler, Sep 27 2017
STATUS
approved