A198190 Primes from the decimal expansion of sqrt(2), sorted first by the final digit index and then by length.

41, 2, 421, 3, 13, 5, 2, 3, 23, 5623, 135623, 42135623, 4142135623, 7, 37, 56237, 3, 73, 373, 3562373, 213562373, 7309, 37309, 5, 5048801, 414213562373095048801, 7, 887, 488016887, 142135623730950488016887, 2, 2, 688724209, 414213562373095048801688724209

Offset

1,1

Links

Table of n, a(n) for n=1..34.

Example

The first digit, 1, is not prime.
The second digit, 4, cannot terminate any prime.
The third digit, 1, is not prime, but 41 is, so a(1) = 41. 141 is not prime, so it is not in the sequence.

Prog

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

Crossrefs

Cf. A002193.

Sequence in context: A283895 A051317 A036189 * A106424 A126636 A095188

Adjacent sequences: A198187 A198188 A198189 * A198191 A198192 A198193

Keyword

nonn,base

Author

Franklin T. Adams-Watters, Oct 21 2011

Status

approved