OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..5000
MATHEMATICA
lst = Cases[Range[1, 100000, 2], n_ /; Mod[n, CarmichaelLambda@ n] == 1 && ! PrimeQ@ n]; Reap@ For[k = 1, k < Length@ lst, k++, Sow@ Count[Range[lst[[k]], lst[[k + 1]]], _?PrimeQ]] // Flatten // Rest (* Michael De Vlieger, Apr 03 2015, after Artur Jasinski at A002997 *)
PROG
(PARI) vi=readvec("b002997.txt")
a(n)=primepi(vi[n+1])-primepi(vi[n])
CROSSREFS
KEYWORD
nonn
AUTHOR
Felix Fröhlich, Apr 01 2015
STATUS
approved