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

Author

Shyam Sunder Gupta, Oct 28 2013

Keywords

• nonn

Examples

			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.
		

Links

• Shyam Sunder Gupta, Table of n, a(n) for n = 1..913
• Jan Feitsma, Tables of pseudoprimes and related data

Crossrefs

Cf. A001567, A230559, A228575, A230668.

Programs

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