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A053683 Number of nonprimes <= prime(n)^2. 1
2, 5, 16, 34, 91, 130, 228, 289, 430, 695, 799, 1150, 1418, 1566, 1880, 2400, 2994, 3202, 3880, 4366, 4624, 5430, 6003, 6921, 8246, 8949, 9315, 10068, 10458, 11246, 14252, 15185, 16628, 17131, 19712, 20254, 21920, 23654, 24846, 26688, 28605 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..41.

FORMULA

a(n) = A000040(n)^2 - A000879(n). - Jean-Christophe Hervé, Oct 27 2013

EXAMPLE

Up to 25 = prime(3)^2, the 16 nonprimes are 1, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 22, 24, 25.

PROG

(PARI) a(n) = prime(n)^2 - primepi(prime(n)^2); \\ Michel Marcus, Oct 28 2013

CROSSREFS

Cf. A000879.

Sequence in context: A139022 A196025 A174988 * A305876 A082085 A179992

Adjacent sequences:  A053680 A053681 A053682 * A053684 A053685 A053686

KEYWORD

easy,nonn

AUTHOR

Labos Elemer, Feb 16 2000

STATUS

approved

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Last modified January 21 21:30 EST 2020. Contains 331128 sequences. (Running on oeis4.)