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A014345 Exponential convolution of primes with themselves. 7

%I #21 Sep 08 2022 08:44:39

%S 4,12,38,118,362,1082,3166,8910,24426,64226,165262,413418,1021362,

%T 2490686,6009150,14401410,34098042,80281962,187356750,432549154,

%U 992941250,2256712462,5088826238,11408805862,25425739346,56383362854,124565557898,274390550594

%N Exponential convolution of primes with themselves.

%H Alois P. Heinz, <a href="/A014345/b014345.txt">Table of n, a(n) for n = 0..1000</a>

%F E.g.f.: (Sum_{k>=0} prime(k+1)*x^k/k!)^2. - _Ilya Gutkovskiy_, Mar 10 2018

%F a(n) = Sum_{j=0..n} binomial(n,j)*prime(j+1)*prime(n-j+1). - _G. C. Greubel_, Jun 07 2019

%p a:= proc(n) option remember; (p-> add(

%p p(j+1)*p(n-j+1)*binomial(n, j), j=0..n))(ithprime)

%p end:

%p seq(a(n), n=0..30); # _Alois P. Heinz_, Mar 10 2018

%t a[n_] := Sum[Prime[j + 1] Prime[n - j + 1] Binomial[n, j], {j, 0, n}];

%t Table[a[n], {n, 0, 30}] (* _Jean-François Alcover_, Jun 05 2018, from Maple *)

%o (Magma) [&+[NthPrime(k+1)*NthPrime(n-k+1)*Binomial(n, k): k in [0..n]]: n in [0..30]]; // _Vincenzo Librandi_, Jun 07 2019

%o (PARI) {a(n) = sum(j=0,n, binomial(n,j)*prime(j+1)*prime(n-j+1))}; \\ _G. C. Greubel_, Jun 07 2019

%o (Sage) [sum(binomial(n,j)*nth_prime(j+1)*nth_prime(n-j+1) for j in (0..n)) for n in (0..30)] # _G. C. Greubel_, Jun 07 2019

%Y Cf. A000040, A014347, A014352.

%K nonn

%O 0,1

%A _N. J. A. Sloane_

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Last modified March 29 01:36 EDT 2024. Contains 371264 sequences. (Running on oeis4.)