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A120068 Numbers n such that n-th prime + 1 is squarefree. 1
1, 3, 6, 10, 12, 13, 18, 21, 26, 29, 30, 33, 37, 40, 42, 44, 50, 55, 59, 60, 65, 66, 71, 74, 77, 78, 79, 80, 82, 84, 88, 89, 97, 100, 104, 110, 112, 113, 116, 119, 121, 122, 123, 127, 130, 134, 135, 136, 139, 142, 145, 147, 148, 151, 158, 159, 160, 165, 168, 169, 172 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

FORMULA

a(n)=primepi(A049097(n))

MATHEMATICA

Select[Range[200], SquareFreeQ[Prime[#]+1]&] (* Harvey P. Dale, Sep 07 2012 *)

CROSSREFS

Cf. A049097.

Sequence in context: A282876 A261662 A050107 * A015875 A301285 A310042

Adjacent sequences:  A120065 A120066 A120067 * A120069 A120070 A120071

KEYWORD

nonn

AUTHOR

Zak Seidov, Aug 15 2006

STATUS

approved

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Last modified March 21 10:13 EDT 2019. Contains 321368 sequences. (Running on oeis4.)