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A071807 Number of pairs (x,y) such that prime(x) - prime(y) = x*tau(x) - y*tau(y), 1<=x<=y<=n. 0

%I

%S 1,2,4,5,7,8,9,10,11,13,14,15,16,18,21,22,23,24,25,26,29,30,31,32,33,

%T 34,36,37,38,39,40,42,43,45,47,48,49,50,52,53,54,55,56,57,58,60,61,62,

%U 63,65,67,69,70,71,73,74,75,76,77,78,79,80,83,84,85,86,87,91,92,94,95

%N Number of pairs (x,y) such that prime(x) - prime(y) = x*tau(x) - y*tau(y), 1<=x<=y<=n.

%o (PARI) for(n=1,130,print1(sum(i=1,n,sum(j=1,i,if(prime(i)-prime(j)-i*numdiv(i)+j*numdiv(j),0,1))),","))

%Y Cf. A000005.

%K nonn

%O 1,2

%A _Benoit Cloitre_, Jun 06 2002

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Last modified April 11 18:59 EDT 2021. Contains 342888 sequences. (Running on oeis4.)