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A093737
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Number of prime pairs below 10^n having a difference of 4.
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3
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0, 7, 40, 202, 1215, 8143, 58621, 440257, 3424679, 27409998, 224373160, 1870585458, 15834656002, 135779962759, 1177207270203, 10304191320776, 90948823579814, 808675898548205
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OFFSET
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1,2
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LINKS
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EXAMPLE
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a(2) = 7 because there are 7 prime gaps of 4 below 10^2.
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PROG
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(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)
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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a(14)-a(18) from S. Herzog's website added by Giovanni Resta, Aug 14 2018
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STATUS
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approved
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