A369059 - OEIS

%I #15 Jan 19 2024 16:55:51

%S 0,1,9,225,11025,1334025,225450225,65155115025,23520996524025,

%T 12442607161209225,10464232622576958225,10056127550296456854225,

%U 13766838616355849433434025,23142055714094182897602596025,42789661015360144177667200050225,94522361182930558488466844910947025,265513312562851938794103367354850193225

%N a(0) = 0, and for n > 0, a(n) is the square of the product of first n-1 odd primes.

%C Terms a(2) .. a(9) are equal to the terms A360435(1..8).

%H <a href="/index/Pri#primorial_numbers">Index entries for sequences related to primorial numbers</a>

%F a(n) = A002620(A002110(n)).

%F For n > 0, a(n) = A061742(n)/4 = A070826(n)^2.

%F For n > 0, a(n) >= A368704(n) and for n > 1, a(n) >= A360435(n-1).

%F For n > 0, A000005(a(n)) = A000244(n-1) = 3^(n-1).

%t Join[{0}, FoldList[Times, 1, Prime[Range[2, 16]]^2]] (* _Amiram Eldar_, Jan 19 2024 *)

%o (PARI)

%o A002110(n) = prod(i=1,n,prime(i));

%o A002620(n) = ((n^2)>>2);

%o A369059(n) = A002620(A002110(n));

%Y Cf. A000005, A000244, A002110, A002620, A061742, A070826, A360435.

%Y An upper bound for A368704, and also for A360435(n-1).

%K nonn

%O 0,3

%A _Antti Karttunen_, Jan 19 2024