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A068007 Least number k such that the number of primes of the form [k/j] for j=1..k (A067514) is n, or zero if impossible. 0
1, 2, 5, 7, 10, 11, 15, 21, 0, 22, 23, 31, 34, 38, 35, 45, 50, 46, 47, 53, 62, 58, 59, 67, 69, 84, 70, 71, 79, 83, 87, 92, 93, 101, 94, 105, 95, 106, 107, 116, 117, 122, 118, 125, 119, 134, 135, 139, 146, 142, 149, 143, 156, 155, 158, 159, 171, 166, 167, 176, 175, 185 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n) = 0 for n = 8, 94, 103, 122, 180, 283, 311, 353, 355, 398, ...

LINKS

Table of n, a(n) for n=0..61.

MATHEMATICA

f[n_] := Count[ PrimeQ[ Floor[ n/Table[i, {i, Floor[n/2]} ]]], True]; a = Table[0, {100} ]; Do[b = f[n]; If[b < 100 && a[[b + 1]] == 0, a[[b + 1]] = n], {n, 1, 300}]; a

CROSSREFS

Cf. A067514.

Sequence in context: A288602 A049842 A018636 * A224870 A033094 A206522

Adjacent sequences:  A068004 A068005 A068006 * A068008 A068009 A068010

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Feb 12 2002

STATUS

approved

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Last modified January 19 23:36 EST 2022. Contains 350466 sequences. (Running on oeis4.)