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a(n) = prime(n)*(prime(n-1) + prime(n+1)).
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%I #63 Feb 08 2023 07:21:01

%S 21,50,112,220,364,544,760,1104,1566,2046,2664,3280,3784,4512,5618,

%T 6726,7686,8844,9940,10950,12324,13944,16020,18430,20200,21424,22684,

%U 23980,26668,30988,34584,36990,39754,43210,46206,49298,52812,56112,59858,63366,66970,71434,74884,77224,81192

%N a(n) = prime(n)*(prime(n-1) + prime(n+1)).

%C 21 is the only semiprime term.

%C All terms after 21 are even.

%F a(n) = A000040(n)*A048448(n).

%F a(n) = A006094(n) + A006094(n-1).

%t Array[Prime[# + 1] (Prime[#] + Prime[# + 2]) &, 45] (* _Michael De Vlieger_, Oct 09 2022 *)

%o (PARI) a(n) = prime(n)*(prime(n-1) + prime(n+1)) \\ _Michel Marcus_, Oct 09 2022

%Y Cf. A000040, A048448, A006094.

%Y Cf. A338529 (first differences).

%K nonn,easy

%O 2,1

%A _Saish S. Kambali_, Oct 09 2022