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A233671
Numbers k such that prime(k)^2 < prime(k-1)*prime(k+1).
8
2, 4, 6, 8, 9, 11, 14, 15, 18, 21, 23, 24, 27, 29, 30, 32, 34, 36, 39, 42, 44, 46, 50, 51, 53, 58, 61, 62, 65, 66, 68, 70, 71, 72, 76, 77, 79, 80, 82, 84, 86, 87, 90, 91, 94, 96, 97, 99, 101, 105, 106, 110, 114, 117, 118, 121, 123, 124, 125, 127, 132, 135
OFFSET
1,1
COMMENTS
If 1 is appended to A046868, the resulting sequence is the complement of A233671. Does A233671 have asymptotic density 1/2? Does every positive integer occur infinitely many times in the difference sequence of A233671?
LINKS
EXAMPLE
a(1) = 2 because 3^2 < 2*5.
MATHEMATICA
Select[Range[2, 200], Prime[#]^2 < Prime[# - 1]*Prime[# + 1] &]
PrimePi[#]&/@Select[Partition[Prime[Range[200]], 3, 1], #[[2]]^2<(#[[1]] #[[3]])&][[All, 2]] (* Harvey P. Dale, Dec 09 2021 *)
CROSSREFS
Sequence in context: A184587 A345436 A225773 * A348854 A143346 A189010
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Dec 14 2013
STATUS
approved