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A172037
Prime partial sums of Sophie Germain primes A005384.
3
2, 5, 73, 167, 2423, 7621, 39233, 50969, 89563, 198139, 207029, 267143, 322963, 335117, 438517, 481207, 541547, 812051, 874697, 917611, 939293, 1077761, 1149593, 1354267, 1464011, 1695559, 1880401, 2510083, 2548703, 3115249, 3157487, 3505849, 4519057
OFFSET
1,1
COMMENTS
a(1) and a(2) are themselves Sophie Germain primes.
LINKS
FORMULA
A000040 INTERSECTION A066819 = {p such that p is prime and SUM[i=1..k]A005384(k) is prime} = {p such that p is prime and SUM[i=1..k]{p is prime and 2p+1 is prime}.}.
EXAMPLE
a(1) = 2 = first Sophie Germain prime A005384(1). a(2) = 5 = sum of first two Sophie Germain primes = 2+3. a(3) = 73 = sum of first six Sophie Germain primes = 2+3+5+11+23+29.
MATHEMATICA
Select[Accumulate[Select[Prime[Range[5000]], PrimeQ[2#+1]&]], PrimeQ] (* Harvey P. Dale, Nov 27 2013 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Jan 23 2010
EXTENSIONS
a(7) - a(34) from Nathaniel Johnston, Apr 29 2011
STATUS
approved