OFFSET
0,2
COMMENTS
Squares of primorials (first definition, A002110).
Exponential superabundant numbers: numbers k with a record value of the exponential abundancy index, A051377(k)/k > A051377(m)/m for all m < k. - Amiram Eldar, Apr 13 2019
Numbers k with a record value of A056170(k), or least number k with A056170(k) = n. - Amiram Eldar, Apr 15 2019
Empirically, these are possibly the denominators for 1 - Sum_{k=1..n} (-1)^(k+1)/prime(k)^2. The numerators are listed in A136370. - Petros Hadjicostas, May 14 2020
a(n) = least k such that rad(k/rad(k)) = A002110(n). - David James Sycamore, Jun 10 2024
LINKS
Harry J. Smith, Table of n, a(n) for n = 0..100
FORMULA
a(n) = Product_{j=1..n} A001248(j). - Alois P. Heinz, May 14 2020
EXAMPLE
a(4) = 2^2 * 3^2 * 5^2 * 7^2 = 44100.
MAPLE
a:= proc(n) option remember; `if`(n=0, 1, ithprime(n)^2*a(n-1)) end:
seq(a(n), n=0..15); # Alois P. Heinz, May 14 2020
MATHEMATICA
a[n_]:=Product[Prime[i]^2, {i, 1, n}]; (* Vladimir Joseph Stephan Orlovsky, Dec 05 2008 *)
PROG
(PARI) for(n=0, 20, print1(prod(k=1, n, prime(k)^2), ", "))
(PARI) { n=-1; m=1; forprime (p=2, prime(101), write("b061742.txt", n++, " ", m^2); m*=p ) } \\ Harry J. Smith, Jul 27 2009
(Magma) [n eq 0 select 1 else (&*[NthPrime(j)^2: j in [1..n]]): n in [0..20]]; // G. C. Greubel, Apr 19 2019
(Sage) [product(nth_prime(j)^2 for j in (1..n)) for n in (0..20)] # G. C. Greubel, Apr 19 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, Jun 21 2001
STATUS
approved