OFFSET
1,2
COMMENTS
LINKS
T. D. Noe, Table of n, a(n) for n = 1..5000
EXAMPLE
When formatted as an array of primes of the form nk+1 up to n^2+1:
2
3,5
7
5,13,17
11
7,13,19,31,37
29,43
17,41
19,37,73
11,31,41,61,71,101
23,67,89
13,37,61,73,97,109
53,79,131,157
29,43,71,113,127,197
The sequence contains the number of terms in the n-th row.
MATHEMATICA
Table[cnt=0; Do[If[PrimeQ[k*n+1], cnt++ ], {k, n}]; cnt, {n, 100}]
Table[Count[n*Range[n]+1, _?PrimeQ], {n, 90}] (* Harvey P. Dale, Jan 24 2014 *)
PROG
(PARI) a(m)=local(c); for(n=1, m, c=0; for(k=1, n, if(isprime(n*k+1), c++; )); print1(c", "))
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), Jun 26 2003
EXTENSIONS
STATUS
approved