A355628 - OEIS

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A355628

a(n) is the number of positive integers p that can be written as p = Product_{i = 1..n} (3 + 1/t_i) with integers t_i >= 2.

0, 2, 7, 25, 96, 364, 1344, 4921

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..8.

EXAMPLE

a(1) = 0 because (3 + 1/t_1) is not integer for t_1 >= 2.

a(2) = 2 because 10 = (3 + 1/4) * (3 + 1/13) and 11 = (3 + 1/2) * (3 + 1/7) and no other positive integer p can be written as p = (3 + 1/t_1) * (3 + 1/t_2) with integers t_1, t_2 >= 2, cf. A355626.

PROG

(PARI) See A355626.

CROSSREFS

Cf. A355626, A355627, A355629, A355630, A355631.

Sequence in context: A150455 A150456 A150457 * A276903 A150458 A150459

Adjacent sequences: A355625 A355626 A355627 * A355629 A355630 A355631

KEYWORD

hard,more,nonn

AUTHOR

Markus Sigg, Jul 15 2022

STATUS

approved