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A084196 Number of primes q<prime(n) such that q+1 divides prime(n)+1. 6
0, 0, 1, 1, 3, 0, 2, 1, 5, 2, 2, 0, 3, 1, 6, 3, 6, 0, 1, 7, 0, 3, 6, 4, 1, 2, 2, 6, 0, 3, 3, 5, 2, 3, 3, 3, 0, 1, 9, 2, 9, 1, 8, 0, 3, 3, 1, 4, 6, 0, 3, 11, 0, 8, 2, 8, 6, 3, 0, 2, 1, 5, 3, 7, 0, 2, 1, 0, 5, 1, 2, 13, 2, 0, 3, 10, 3, 0, 2, 0, 11, 0, 11, 2, 5, 5, 6, 0, 4, 2, 6, 13, 2, 5, 2, 13, 4, 4, 1, 0, 1, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

a(A049084(A082539(n)))=0, a(A049084(A084197(n)))>0, a(A049084(A084198(n)))=1;

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

EXAMPLE

n=5, prime(5)=11: (11+1) mod (q+1) = 0 for 3 primes q<11: 2, 3,

and 5, therefore a(5)=3.

PROG

(Haskell)

a084196 n = a084196_list !! (n-1)

a084196_list = f [] a000040_list where

   f ps' (p:ps) = length [q | q <- ps', mod (p + 1) (q + 1) == 0] :

                  f (p : ps') ps where

-- Reinhard Zumkeller, Jan 06 2014

CROSSREFS

Cf. A084198, A084200.

Sequence in context: A268464 A165066 A034389 * A295041 A127913 A135991

Adjacent sequences:  A084193 A084194 A084195 * A084197 A084198 A084199

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, May 18 2003

STATUS

approved

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Last modified December 3 23:53 EST 2020. Contains 338920 sequences. (Running on oeis4.)