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A317398 Positive integers that have exactly eight representations of the form 1 + p1 * (1 + p2* ... * (1 + p_j)...), where [p1, ..., p_j] is a (possibly empty) list of distinct primes. 2
2991, 3004, 3319, 3554, 3928, 4846, 5552, 5886, 6293, 6784, 7183, 7286, 7396, 7668, 7741, 7743, 7829, 7996, 8095, 8121, 8212, 8477, 8586, 8614, 8856, 8861, 9096, 9307, 9374, 9591, 9626, 9636, 9637, 9721, 9738, 9845, 9891, 9912, 9934, 10011, 10024, 10048, 10251 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 1..20000

FORMULA

A317241(a(n)) = 8.

MAPLE

b:= proc(n, s) option remember; local p, r; if n=1 then 1 else r:=0;

      for p in numtheory[factorset](n-1) minus s while r<9

        do r:= r+b((n-1)/p, s union {p}) od; `if`(r<9, r, 9)

      fi

    end:

a:= proc(n) option remember; local k; for k from

     `if`(n=1, 1, 1+a(n-1)) while b(k, {})<>8 do od; k

    end:

seq(a(n), n=1..100);

CROSSREFS

Column k=8 of A317390.

Cf. A317241.

Sequence in context: A159731 A221725 A205241 * A253962 A253955 A253758

Adjacent sequences:  A317395 A317396 A317397 * A317399 A317400 A317401

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Jul 27 2018

STATUS

approved

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Last modified May 7 23:48 EDT 2021. Contains 343652 sequences. (Running on oeis4.)