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Greatest prime p such that prime(n)+p <= prime(n+1); a(1)=1.
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%I #7 Aug 04 2024 19:59:14

%S 1,2,2,3,2,3,2,3,5,2,5,3,2,3,5,5,2,5,3,2,5,3,5,7,3,2,3,2,3,13,3,5,2,7,

%T 2,5,5,3,5,5,2,7,2,3,2,11,11,3,2,3,5,2,7,5,5,5,2,5,3,2,7,13,3,2,3,13,

%U 5,7,2,3,5,7,5,5,3,5,7,3,7,7,2,7,2,5,3,5,7,3,2,3,11,7,3,7,3,5,11,2,17

%N Greatest prime p such that prime(n)+p <= prime(n+1); a(1)=1.

%C a(n) = A007917(A001223(n)) for n>1.

%t Join[{1},NextPrime[#+1,-1]&/@Differences[Prime[Range[2,100]]]] (* _Harvey P. Dale_, Aug 04 2024 *)

%Y Cf. A001223, A007917.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Oct 23 2003