OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
The first and second primes of the form 4*k+1 are 5 and 13, so a(1) = (13-5)/4 = 2.
MATHEMATICA
k=0; m=4; r=1; Do[s=Mod[Prime[n], m]; If[Equal[s, r], rp=ep; k=k+1; ep=Prime[n]; Print[(ep-rp)/4]; ], {n, 1, 1000}]
Differences[Select[4*Range[1000]+1, PrimeQ]]/4 (* Harvey P. Dale, Dec 04 2011 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Apr 07 2003
STATUS
approved