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A050108 a(n) = floor(a(n-1)/4) if this is positive and not yet in the sequence, otherwise a(n) = 5*a(n-1). 8
1, 5, 25, 6, 30, 7, 35, 8, 2, 10, 50, 12, 3, 15, 75, 18, 4, 20, 100, 500, 125, 31, 155, 38, 9, 45, 11, 55, 13, 65, 16, 80, 400, 2000, 10000, 2500, 625, 156, 39, 195, 48, 240, 60, 300, 1500, 375, 93, 23, 115, 28, 140, 700, 175, 43, 215 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

MATHEMATICA

Rest@Nest[Append[#, If[FreeQ[#, r = Quotient[#[[-1]], 4]], r, 5 #[[-1]]]] &, {0, 1}, 55] (* Ivan Neretin, Jul 31 2016 *)

PROG

(PARI) first(n)=my(v=vector(n), t); v[1]=1; for(i=2, n, t=v[i-1]\4; if(t<2, v[i]=5*v[i-1]; next); for(j=1, i-1, if(v[j]==t, v[i]=5*v[i-1]; next(2))); v[i]=t); v \\ Charles R Greathouse IV, Jul 31 2016

CROSSREFS

Cf. A050000 and references therein.

Sequence in context: A070387 A331272 A123748 * A070386 A050084 A070379

Adjacent sequences:  A050105 A050106 A050107 * A050109 A050110 A050111

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved

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Last modified August 3 08:10 EDT 2020. Contains 336197 sequences. (Running on oeis4.)