OFFSET
1,3
COMMENTS
Conjecture: All items of this sequence are greater than or equal to 1. Tested to prime(1000000).
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
EXAMPLE
Prime(1)*2-2 = 2, so a(1)=1;
Prime(3) = 5, 5*3-2 = 13, 5*5-2 = 23, so a(3)=2;
MATHEMATICA
Table[p=Prime[n]; ct=0; Do[pk=Prime[k]; If[PrimeQ[p*pk-2], ct=ct+1], {k, n}]; ct, {n, 100}]
PROG
(Haskell)
a103960 n = sum [a010051' $ p * q - 2 |
let p = a000040 n, q <- takeWhile (<= p) a000040_list]
-- Reinhard Zumkeller, Jul 30 2015
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Lei Zhou, Feb 22 2005
STATUS
approved