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Smallest subscript j such that d=p[p(j+1)]-p[p(j)]=2n, or 0 if j does not exist (at d=4).
2

%I #5 Oct 15 2013 22:31:25

%S 1,0,2,7,5,13,4,8,6,14,12,27,9,51,11,40,21,16,25,39,36,96,58,18,132,

%T 134,56,106,108,72,34,102,42,158,202,68,53,118,121,46,124,101,383,91,

%U 157,30,80,97,204,126,258,139,381,145,222,47,62,240,242,363,66,177,565

%N Smallest subscript j such that d=p[p(j+1)]-p[p(j)]=2n, or 0 if j does not exist (at d=4).

%F a(n)=Min{x : A073131[x]=2n}

%e d=20 appears first at n=14, p(15)=47,p(14)=43, d=p(47)-p(43)=211-191=20, so a(20/2)=a(10)=14.

%t t=Table[0, {100}]; Do[s = Prime[ Prime[x+1]] - Prime[ Prime[x]]; If[ s < 202 && t[[s/2]]==0, t[[s/2]]=n], {n, 1, 1000}]; t

%Y Cf. A073130, A073131.

%K nonn

%O 1,3

%A _Labos Elemer_, Jul 16 2002

%E Edited by _Robert G. Wilson v_, Jul 17 2002