

A091974


Let R_{k}(n) = the digit reversal of n in base k (R_{k}(n) is written in base 10). a(n) is the number of distinct values of R_{k}(n) arising if k=2,..,n+1.


4



1, 1, 2, 2, 2, 3, 5, 5, 5, 6, 7, 9, 9, 11, 11, 12, 11, 14, 13, 16, 16, 17, 19, 21, 19, 22, 22, 21, 23, 24, 27, 27, 27, 29, 29, 32, 29, 35, 33, 36, 32, 38, 37, 41, 39, 41, 40, 42, 41, 45, 43, 45, 46, 48, 47, 49, 50, 52, 52, 55, 53, 57, 58, 56, 57, 59, 60, 61
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OFFSET

0,3


LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..10000
Rémy Sigrist, Density plot of (n, R_k(n)) for n = 0..1000 and k >= 2


MATHEMATICA

rev[x_, b_]:=FromDigits[Reverse[IntegerDigits[x, b]], b]
Length /@ Union /@ Table[Table[rev[x, b], {b, 2, x + 1}], {x, 1, 200}] (* Dylan Hamilton, Oct 16 2010 *)


PROG

(PARI) a(n) = #Set(apply(b > fromdigits(Vecrev(digits(n, b)), b), [2..max(2, n+1)])) \\ Rémy Sigrist, Jan 29 2020


CROSSREFS

Cf. A004086, A030101A030108, A056960A056963, A181385.
Sequence in context: A228390 A309256 A095972 * A029073 A058618 A135213
Adjacent sequences: A091971 A091972 A091973 * A091975 A091976 A091977


KEYWORD

nonn,base


AUTHOR

Naohiro Nomoto, Mar 14 2004


STATUS

approved



