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 A198189 Primes from the decimal expansion of the golden ratio, phi, sorted first by the final digit index and then by length. 0

%I

%S 61,3,3,1618033,7,887,9887,39887,339887,1618033988749,89,8874989,

%T 398874989,803398874989,61803398874989,2,5,3,83,683,458683,3,43,5,3,

%U 563,6563,36563,868343656381,180339887498948482045868343656381,11,811,58683436563811

%N Primes from the decimal expansion of the golden ratio, phi, sorted first by the final digit index and then by length.

%e For the first two digits, none of 1, 6, and 16 are prime.

%e The next digit, 1 is not prime, but 61 is, so a(1) = 61. 161 is not prime, so it is not included.

%o (PARI) v=[1, 6, 1, 8, 0, 3, 3, 9, 8, 8, 7, 4, 9, 8, 9, 4, 8, 4, 8, 2, 0, 4, 5, 8, 6, 8, 3, 4, 3, 6, 5, 6, 3, 8, 1, 1]

%o for(n=1,#v,x=0;p=1;forstep(k=n,1,-1,x+=p*v[k];p*=10;if(v[k]&&isprime(x),print1(x", "))))

%Y Cf. A186205.

%K nonn,base

%O 1,1

%A _Franklin T. Adams-Watters_, Oct 21 2011

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Last modified August 17 05:07 EDT 2022. Contains 356184 sequences. (Running on oeis4.)