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%I #6 Sep 13 2015 23:52:24
%S -1,2,8,15,22,31,41,53,63,77,90,105,123,138,157,175,194,215,237,259,
%T 281,306,330,355,382,410,437,468,498,527,558,588,623,656,689,727,762,
%U 797,836,872,911,952,992,1033,1076,1119,1161,1205,1249,1294,1341,1390,1434,1483,1534,1585,1634,1687,1738,1791,1842,1898
%N Largest index-sum i+j such that prime(i)+prime(j)=4*n^2. a(0)=-1 to indicate that there is no such pair of primes.
%F a(n)= max(i+j), 1<=i<=j: A000040(i)+A000040(j)=A016742(n). - _R. J. Mathar_, Apr 22 2008
%p A133230 := proc(n) local a016742,i,j,a ; a016742 := 4*n^2 ; a := -1 ; if n =0 then RETURN(-1) ; fi ; for i from 1 to numtheory[pi](a016742-1) do if isprime(a016742-ithprime(i)) then j := numtheory[pi](a016742-ithprime(i)) : a := max(a,i+j) ; fi ; od: RETURN(a) ; end: seq(A133230(n),n=0..80) ; # _R. J. Mathar_, Apr 22 2008
%Y Cf. A000040, A005843, A016742, A113631, A133229.
%K sign
%O 0,2
%A _Alexander R. Povolotsky_, Dec 19 2007
%E Edited and extended by _R. J. Mathar_, Apr 22 2008