A127601 Integer part of 4th root of product of first n primes.

1, 1, 1, 2, 3, 6, 13, 26, 55, 122, 283, 669, 1650, 4176, 10694, 28002, 75555, 209402, 585212, 1674296, 4860120, 14206194, 42353033, 127836257, 392646335, 1232237672, 3906383039, 12444691408, 40024883480, 129326254765

Offset: 0

Author

Artur Jasinski, Jan 19 2007

Keywords

• nonn

Comments

For n>=6, a(n) >= prime(n+1).

a(n) gives the number of pairs within A002110(n) of the form {x, x^4} where x is nonzero positive integer. - Soumyadeep Dhar, May 16 2021

Links

• Soumyadeep Dhar, Table of n, a(n) for n = 0..1154

Crossrefs

Cf. A002110, A060797, A127600, A127602, A127603, A127604.

Programs

Mathematica

a = {}; Do[b = 1; Do[b = b Prime[x], {x, 1, n}]; AppendTo[a, Floor[b^(1/4)]], {n, 1, 50}]; a

PARI

a(n)={sqrtnint(vecprod(primes(n)), 4)} \\ Andrew Howroyd, Apr 27 2021

Extensions

a(0)=1 prepended by Soumyadeep Dhar, Apr 28 2021