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A075420 Trajectory of n under the Reverse and Add! operation carried out in base 4 (presumably) does not reach a palindrome. 8
290, 318, 378, 381, 438, 444, 462, 498, 501, 504, 510, 545, 567, 573, 627, 633, 636, 639, 693, 696, 699, 717, 719, 732, 751, 753, 756, 759, 765, 775, 795, 799, 800, 822, 823, 828, 835, 847, 859, 882, 883, 888, 894, 895, 915, 919, 927, 948, 954, 967, 972 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Base-4 analog of A023108 (base 10) and A066059 (base 2).

LINKS

A.H.M. Smeets, Table of n, a(n) for n = 1..20000

Index entries for sequences related to Reverse and Add!

MATHEMATICA

limit = 10^3; (* Assumes that there is no palindrome if none is found before "limit" iterations *)

Select[Range[1000],

Length@NestWhileList[# + IntegerReverse[#, 4] &, #, # !=

IntegerReverse[#, 4]  &, 1, limit] == limit + 1 &] (* Robert Price, Oct 16 2019 *)

PROG

(PARI) {stop=1000; for(n=1, 980, k=n; c=0; while(c<stop, a=k; rev=0; while(a>0, d=divrem(a, 4); a=d[1]; rev=4*rev+d[2]); if(rev==k, c=stop+1, k=k+rev; c++)); if(c==stop, print1(n, ", ")))}

CROSSREFS

Cf. A023108, A066059, A075421, A075299, A075153.

Sequence in context: A091680 A129245 A186553 * A075421 A332229 A296055

Adjacent sequences:  A075417 A075418 A075419 * A075421 A075422 A075423

KEYWORD

base,nonn

AUTHOR

Klaus Brockhaus, Sep 18 2002

EXTENSIONS

Offset changed to 1 by A.H.M. Smeets, Feb 10 2019

STATUS

approved

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Last modified September 17 22:14 EDT 2021. Contains 347489 sequences. (Running on oeis4.)