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A114432 Primes of the form 1 + product of the first n 4-almost primes A014613. 0
17, 8126654054401 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The next term is too large to display here. - N. J. A. Sloane, Jul 30 2009

4-almost prime analog of primorial primes A005234 (primes p such that 1 + product of primes up to p is prime) as indexed by A014545 (n such that n-th Euclid number (A006862(n)) = 1 + (Product of first n primes) is prime). In that sense, this sequence is indexed by (1, 8, ...). No more through product of first 16 of the 4-almost primes.

Terms are one more than the products of 4-almost primes up to 16, 81, 294, 513, 825, 1356, 1612, 2004, 2756, 7714, ... - Charles R Greathouse IV, Jul 28 2009

LINKS

Table of n, a(n) for n=1..2.

FORMULA

{a(n)} = {1 + Prod[from i = 1 to n] A014613(i)} INTERSECTION {A000040}.

EXAMPLE

a(1) = 17 because 1 + 16 = 1 + A014613(1) = 1 more than the first 4-almost prime is itself prime.

a(2) = 8126654054401 = 1 + (16 * 24 * 36 * 40 * 54 * 56 * 60 * 81) = 1 more than the product of the first 8 of the 4-almost primes and is prime.

CROSSREFS

Cf. A000040, A001358, A014612, A002110, A005234, A014545, A112141.

Sequence in context: A013882 A271562 A157255 * A134686 A257305 A128398

Adjacent sequences:  A114429 A114430 A114431 * A114433 A114434 A114435

KEYWORD

nonn,bref

AUTHOR

Jonathan Vos Post, Feb 13 2006

STATUS

approved

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Last modified June 20 17:27 EDT 2019. Contains 324234 sequences. (Running on oeis4.)