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 A049040 Number of Sophie Germain primes <= Prime[ 10^n ]. 1
 6, 26, 167, 1222, 9668, 82237, 711154, 6284076 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Sophie Germain primes are primes p such that 2p+1 is also prime. LINKS EXAMPLE The first 10 primes are 2,3,5,7,11,13,17,23,29 and 31. 6 of these are Sophie Germain primes, namely: 2,3,5,11,23 and 29. MATHEMATICA << NumberTheory`NumberTheoryFunctions`; cnt = 0; currentPrime = 1; For[ i = 1, i == i, i ++, currentPrime = NextPrime[ currentPrime ]; If[ PrimeQ[ 2*currentPrime + 1 ], cnt++ ]; If[ IntegerQ[ Log[ 10, i ] ], Print[ cnt ] ]; ] CROSSREFS Sequence in context: A144037 A187458 A100308 * A103649 A053946 A211946 Adjacent sequences:  A049037 A049038 A049039 * A049041 A049042 A049043 KEYWORD nonn AUTHOR Dennis S. Kluk (mathemagician(AT)ameritech.net) EXTENSIONS More terms from Alex Healy, Mar 19 2001 STATUS approved

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Last modified October 20 22:44 EDT 2019. Contains 328291 sequences. (Running on oeis4.)