A191583 Sum of the distinct prime divisors of prime(n) + prime(n+1).

5, 2, 5, 5, 5, 10, 5, 12, 15, 10, 19, 18, 12, 10, 7, 9, 10, 2, 28, 5, 21, 5, 45, 36, 16, 22, 17, 5, 42, 10, 48, 69, 28, 5, 10, 20, 7, 21, 24, 13, 10, 36, 5, 23, 16, 48, 40, 10, 24, 23, 61, 10, 46, 129, 20, 28, 10, 139, 36, 52, 5, 10, 108, 18, 17, 5, 169, 24

Offset: 1

Author

Michel Lagneau, Jun 07 2011

Keywords

• nonn

Comments

a(n) = A008472(A001043(n)). [Reinhard Zumkeller, Jun 28 2011]

Examples

			a(6) = 10 because prime(6) + prime(7) = 13+17 = 30 = 2*3*5 and 2+3+5 = 10.
		

Links

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

Programs

Maple

with(numtheory):for n from 1 to 100 do:x:=ithprime(n)+ithprime(n+1):y:=factorset(x):n1:=nops(y):s:=0:for  k from 1 to n1 do:s:=s+y[k]:od:printf(`%d, `,s):od:

Mathematica

sdpd[n_]:=Total[Transpose[FactorInteger[n]][[1]]]; sdpd/@(Total/@ Partition[ Prime[Range[70]],2,1]) (* Harvey P. Dale, Mar 18 2012 *)

PARI

vecsum(v)=sum(i=1,#v,v[i])
p=2;forprime(q=3,1e3,print1(vecsum(factor(p+q)[,1])", ");p=q)
\\ Charles R Greathouse IV, Jun 12 2011