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A093737 Number of prime pairs below 10^n having a difference of 4. 1
0, 7, 40, 202, 1215, 8143, 58621, 440257, 3424679 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

FORMULA

Count prime pairs below 10^n having a difference of 4

EXAMPLE

a(2)=7 because there are 7 prime gaps of 4 below 10^2

PROG

UBASIC: 20 N=1:dim T(34); 30 A=nxtprm(N); 40 N=A; 50 B=nxtprm(N); 60 D=B-A; 70 for x=2 to 34 step 2; 80 if D=X and B<10^2+1 then T(X)=T(X)+1; 90 next X; 100 if B>10^2+1 then 140; 110 B=A; 120 N=N+1; 130 goto 30; 140 for x=2 to 34 step 2; 150 print T(X); , 160 next (This program simultaneously finds values from 2 to 34 -- if gap=2 add 1-- adjust lines 80 and 100 for desired 10^n)

CROSSREFS

Cf. A007508 A093738.

Sequence in context: A164083 A096200 A055282 * A081039 A083327 A026716

Adjacent sequences:  A093734 A093735 A093736 * A093738 A093739 A093740

KEYWORD

easy,nonn

AUTHOR

Enoch Haga (Enokh(AT)comcast.net), Apr 15 2004

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Last modified February 16 02:30 EST 2012. Contains 205860 sequences.