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A023862 a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t = A008578 ({1} U primes). 1

%I

%S 1,2,7,11,26,40,76,104,171,219,331,397,566,672,912,1046,1369,1561,

%T 1985,2223,2762,3026,3688,4030,4833,5215,6179,6631,7764,8318,9630,

%U 10270,11793,12499,14245,15019,17006,17930,20176,21182,23701,24837,27645,28965,32084,33504

%N a(n) = 1*t(n) + 2*t(n-1) + ... + k*t(n+1-k), where k=floor((n+1)/2) and t = A008578 ({1} U primes).

%H G. C. Greubel, <a href="/A023862/b023862.txt">Table of n, a(n) for n = 1..1000</a>

%t Join[{1}, Table[Sum[j*Prime[n-j], {j,1,Floor[(n+1)/2]}], {n, 2, 50}]] (* _G. C. Greubel_, Jun 12 2019 *)

%o (PARI) a(n) = sum(j=1, floor((n+1)/2), j*prime(n-j));

%o vector(50, n, if(n==1, 1, a(n))) \\ _G. C. Greubel_, Jun 12 2019

%o (MAGMA) [1] cat [(&+[j*NthPrime(n-j): j in [1..Floor((n+1)/2)]]): n in [2..50]]; // _G. C. Greubel_, Jun 12 2019

%o (Sage) [1]+[sum(j*nth_prime(n-j) for j in (1..floor((n+1)/2))) for n in (2..50)] # _G. C. Greubel_, Jun 12 2019

%Y CF. A000040, A008578.

%K nonn

%O 1,2

%A _Clark Kimberling_

%E Title simplified by _Sean A. Irvine_, Jun 12 2019

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Last modified October 18 06:01 EDT 2021. Contains 348065 sequences. (Running on oeis4.)