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 A055738 Number of prime quadruples < 10^n, where a prime quadruple means 4 successive primes {p, p', p'', p'''} with p''' = p + 8. 1

%I

%S 0,3,6,13,39,167,900,4769,28389

%N Number of prime quadruples < 10^n, where a prime quadruple means 4 successive primes {p, p', p'', p'''} with p''' = p + 8.

%D J. Recreational Math., vol. 23, No. 2, 1991, p. 97.

%H <a href="/index/Pri#primepop">Index entries for sequences related to numbers of primes in various ranges</a>

%e For n=2 the quadruples are 3,5,7,11; 5,7,11,13; 11,13,17,19.

%p with(numtheory): x := 1229; t1 := [seq(ithprime(i),i=1..x)]; c := 0: for i from 1 to x-3 do if t1[i]+8 = t1[i+3] then c := c+1; fi; od: c; # the values of x to use are given by A006880.

%t x=168; a=Table[ Prime[ n ], {n, 1, x} ]; c=0; Do[ If[ a[ [ n ] ]+8==a[ [ n+2 ] ], c++ ], {n, 1, x-3} ]; # the values of x to use are given by A006880.

%Y Cf. A055737, A006880.

%K more,nonn

%O 1,2

%A _Robert G. Wilson v_, Jun 09 2000

%E 2 more terms from _Jud McCranie_, Oct 08 2000.

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