A230715 Smallest numbers in a set of 4 consecutive odd numbers that are primes or pseudoprime (base 2).

641, 656597, 6212357, 18958567877, 287468425241, 626160901277, 634038307447, 1395494019917, 1925525109197, 1960708164797, 1962378065897, 1977370759361, 2788325761547, 3032013857177, 4846359321103, 6877227801077, 11927878640383, 20835183400303, 22298617759877

Offset

1,1

Links

Shyam Sunder Gupta, Table of n, a(n) for n = 1..913

Jan Feitsma, Tables of pseudoprimes and related data

Example

656597 is in sequence because 656597, 656599, 656601, 656603 is a set of 4 consecutive odd number where 656601 is pseudoprime base 2 and others are prime.

Prog

(PARI) \\ Import A001567 into the vector v
for(i=1, #v, start=stop=v[i]; while(ok(start-=2), ); while(ok(stop+=2), ); while(stop-start>9, print1(start+=2, ", "))) \\ Charles R Greathouse IV, Oct 28 2013

Crossrefs

Cf. A001567, A230559, A228575, A230668.

Sequence in context: A206378 A229851 A268840 * A135384 A253420 A289649

Adjacent sequences: A230712 A230713 A230714 * A230716 A230717 A230718

Keyword

nonn

Author

Shyam Sunder Gupta, Oct 28 2013

Status

approved