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A024697 a(n) = p(1)p(n) + p(2)p(n-1) + ... + p(k)p(n+1-k), where k = [ (n+1)/2 ], p = A000040 = the primes.

%I A024697 #13 Apr 07 2014 07:57:42
%S A024697 4,6,19,29,68,94,177,231,400,484,753,903,1340,1552,2157,2489,3352,
%T A024697 3784,5013,5515,7052,7758,9773,10575,13076,14076,17023,18339,21876,
%U A024697 23414,27715,29437,34570,36500,42335,44731,51560,54198,61955,65051,73700,77402,87293
%N A024697 a(n) = p(1)p(n) + p(2)p(n-1) + ... + p(k)p(n+1-k), where k = [ (n+1)/2 ], p = A000040 = the primes.
%C A024697 a(n) = A025129(n) for even n. - _M. F. Hasler_, Apr 06 2014
%H A024697 Reinhard Zumkeller, <a href="/A024697/b024697.txt">Table of n, a(n) for n = 1..10000</a>
%p A024697 A024697:=n->sum( ithprime(k)*ithprime(n-k+1), k=1..(n+1)/2 ); seq(A024697(n), n=1..50); # _Wesley Ivan Hurt_, Apr 06 2014
%t A024697 Table[Sum[Prime[k] Prime[n - k + 1], {k, (n + 1)/2}], {n, 50}] (* _Wesley Ivan Hurt_, Apr 06 2014 *)
%o A024697 (PARI) A024697(n)=sum(k=1, (n+1)\2, prime(k)*prime(n-k+1)) \\ _M. F. Hasler_, Apr 06 2014
%o A024697 (Haskell)
%o A024697 a024697 n = a024697_list !! (n-1)
%o A024697 a024697_list = f (tail a000040_list) [head a000040_list] 2 where
%o A024697    f (p:ps) qs k = sum (take (div k 2) $ zipWith (*) qs $ reverse qs) :
%o A024697                    f ps (p : qs) (k + 1)
%o A024697 -- _Reinhard Zumkeller_, Apr 07 2014
%Y A024697 Cf. A014342, A000040.
%K A024697 nonn
%O A024697 1,1
%A A024697 _Clark Kimberling_
%E A024697 Name edited and values double-checked by _M. F. Hasler_, Apr 06 2014