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A186205
The first n-digit prime in the decimal expansion of the golden ratio.
1
3, 61, 887, 9887, 39887, 339887, 1618033, 65638117, 398874989, 1772030917, 38622235369, 803398874989, 1618033988749, 61803398874989, 586834365638117, 8343656381177203, 69317931800607667, 484754088075386891
OFFSET
1,1
COMMENTS
The Golden ratio is (1+sqrt(5))/2 = 1.618033988749894848204586834....
MAPLE
Digits := 10000: p0 := evalf((1+sqrt(5))/2):for d from 1 to 20 do: id:=0:for
i from 0 to 50000 while(id=0) do :q0:=trunc(p0*10^(i+d-1)): x:= irem(q0, 10^d):
if type(x, prime)=true and length(x)=d then printf(`%d, `, x):id:=1: else fi:od:od:
MATHEMATICA
With[{c=RealDigits[GoldenRatio, 10, 100000][[1]]}, FromDigits/@Table[ SelectFirst[ Partition[c, n, 1], PrimeQ[FromDigits[#]] && IntegerLength[ FromDigits[#]]==n&], {n, 18}]] (* Harvey P. Dale, Aug 21 2017 *)
CROSSREFS
Cf. A001622.
Sequence in context: A102720 A120308 A279381 * A224451 A239792 A009476
KEYWORD
nonn,base
AUTHOR
Michel Lagneau, Feb 15 2011
STATUS
approved