OFFSET
1,1
COMMENTS
The odd primes q minimizing prime(n)*q + prime(n) + q are listed in A225581.
LINKS
John-Å. W. Olsen, Table of a(n), for n = 1..1000
FORMULA
a(n) = (1+prime(n))*A225581(n) + prime(n).
EXAMPLE
a(1) = 11 because prime(1) = 2 and the minimal prime of the form 2*q+2+q with q an odd prime is 11 = 2*3+2+3.
MATHEMATICA
a[n_] := Block[{q = 3, v, p = Prime@n}, While[! PrimeQ[v = p q + p + q], q = NextPrime@q]; v]; Array[a, 50] (* Giovanni Resta, May 11 2013 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
John-Å. W. Olsen, May 11 2013
EXTENSIONS
a(26)-a(50) from Giovanni Resta, May 11 2013
STATUS
approved