

A187713


Base5 Keith numbers.


8



5, 9, 10, 11, 13, 15, 20, 22, 31, 40, 43, 53, 62, 71, 84, 93, 124, 154, 221, 483, 3044, 18748, 125973, 232085, 1705260, 2091605, 5616236, 8067806, 8849508, 58944155, 84572166, 164487062, 421825427, 469435978, 744740232
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

Among bases b = 2 to 36, in b = 5 there is the third highest percentage of Keith numbers between b and b^3 (that is, numbers with two or three digits); only binary and ternary have more Keith numbers in that range.


LINKS

Table of n, a(n) for n=1..35.


EXAMPLE

a(2) = 9. In base 5, the number 9 is written 14, and the second order linear recurrence is then 1, 4, 5, 9, ... therefore 9 is a Keith number in base 5.
The number 14 is a Keith number in base 10 but not base 5, as we have: 2, 4, 6, 10, 16, ...


MATHEMATICA

(* First run the program for A186830 to define keithSeq *) Select[Range[5, 10^6], Last[keithSeq[#, 5]] == # &]


CROSSREFS

Cf. A007629, base10 Keith numbers; A162724, binary Keith numbers.
Sequence in context: A205712 A093711 A163670 * A101082 A277706 A166934
Adjacent sequences: A187710 A187711 A187712 * A187714 A187715 A187716


KEYWORD

nonn,base


AUTHOR

Alonso del Arte, Mar 17 2011


EXTENSIONS

Extended by T. D. Noe, Mar 23 2011


STATUS

approved



