

A080840


Number of cousin primes < 10^n.


2



1, 8, 41, 203, 1216, 8144, 58622, 440258, 3424680, 27409999, 224373161, 1870585459
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OFFSET

1,2


COMMENTS

The corresponding numbers for twin primes and sexy primes are in A007508 and A080841, the greater of twin primes, cousin primes and sexy primes are in A006512, A046132 and A046117 respectively.


LINKS

Table of n, a(n) for n=1..12.
Eric Weisstein's World of Mathematics, Cousin Primes.
A. Granville, G. Martin, Prime number races, Amer. Math. Monthly vol 113, no 1 (2006) p 1.


PROG

(PARI) {c=0; p=5; for(n=1, 9, while(p<10^n, if(isprime(p4), c++); p=nextprime(p+1)); print1(c, ", "))}


CROSSREFS

Cf. A007508, A080841, A006512, A046132, A046117.
Sequence in context: A273070 A273145 A273176 * A199846 A188180 A026968
Adjacent sequences: A080837 A080838 A080839 * A080841 A080842 A080843


KEYWORD

nonn


AUTHOR

Jason Earls (zevi_35711(AT)yahoo.com), Mar 28 2003


EXTENSIONS

a(8) and a(9) from Klaus Brockhaus, Mar 30 2003
More terms from R. J. Mathar, Aug 05 2007


STATUS

approved



