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%I #13 Sep 08 2022 08:44:47
%S 2,3,11,17,40,56,104,136,219,265,397,475,672,776,1046,1198,1561,1755,
%T 2223,2443,3026,3316,4030,4352,5215,5605,6631,7119,8318,8878,10270,
%U 10892,12499,13183,15019,15847,17930,18836,21182,22210,24837,26039,28965,30267,33504
%N a(n) = 1*prime(n) + 2*prime(n-1) + ... + k*prime(n+1-k), where k=floor((n+1)/2) and prime(n) is the n-th prime.
%C Also, a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (natural numbers), t = (1, p(1), p(2), ... ).
%H G. C. Greubel, <a href="/A023870/b023870.txt">Table of n, a(n) for n = 1..1000</a>
%t Table[Sum[j*Prime[n+1-j], {j,1,Floor[(n+1)/2]}], {n, 1, 50}] (* _G. C. Greubel_, Jun 12 2019 *)
%o (PARI) {a(n) = sum(j=1, floor((n+1)/2), j*prime(n+1-j))}; \\ _G. C. Greubel_, Jun 12 2019
%o (Magma) [(&+[j*NthPrime(n+1-j): j in [1..Floor((n+1)/2)]]): n in [1..50]]; // _G. C. Greubel_, Jun 12 2019
%o (Sage) [sum(j*nth_prime(n+1-j) for j in (1..floor((n+1)/2))) for n in (1..50)] # _G. C. Greubel_, Jun 12 2019
%K nonn
%O 1,1
%A _Clark Kimberling_
%E Title simplified by _Sean A. Irvine_, Jun 12 2019
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