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A202338 Smallest Fibonacci number which when appended to n produces a prime number. 1
1, 3, 1, 1, 3, 1, 1, 3, 377, 1, 3, 13, 1, 89, 1, 3, 3, 1, 1, 89, 1, 3, 3, 1, 1, 3, 1, 1, 3, 89, 1, 21, 1, 13, 3, 13, 3, 3, 89, 1, 233, 1, 1, 3, 13, 1, 21, 13, 1, 3, 13, 1, 233, 1, 21, 3, 1, 13, 3, 1, 3, 21, 1, 1, 3, 1, 3, 3, 1, 1, 21, 13, 3, 3, 1, 1, 3, 233 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..78.

Michel Lagneau, Table of n, a(n) for n = 1..5000

EXAMPLE

a(9) = 377 because 9 concatenated with 377 gives the prime 9377.

MAPLE

with(combinat, fibonacci):for n from 1 to 80 do: i:=0:for m from 1 to 2000 while(i=0) do:p:=fibonacci(m): nn:=length(p): x:=n*10^nn+p: if type(x, prime)=true then i:=1: printf(`%d, `, p):else fi:od:od:

MATHEMATICA

f[n_]:=Block[{p=1, a=IntegerDigits[n]}, While[!PrimeQ[FromDigits[Join[a, IntegerDigits[Fibonacci[p]]]]], p++]; Fibonacci[p]]; Table[f[n], {n, 92}]

With[{fibs=Fibonacci[Range[20]], nn=80}, Table[SelectFirst[fibs, PrimeQ[ n*10^ IntegerLength[ #]+ #]&], {n, nn}]] (* Harvey P. Dale, Feb 28 2020 *)

CROSSREFS

Cf. A000045.

Sequence in context: A068695 A110787 A325982 * A139002 A251913 A285012

Adjacent sequences:  A202335 A202336 A202337 * A202339 A202340 A202341

KEYWORD

nonn,base

AUTHOR

Michel Lagneau, Dec 17 2011

STATUS

approved

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Last modified June 18 23:58 EDT 2021. Contains 345125 sequences. (Running on oeis4.)