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A169695 a(n) = 1 if n is a square, otherwise a(n) = 2. 6
1, 1, 2, 2, 1, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Also number of central divisors of n, if n >= 1. - Omar E. Pol, Feb 10 2011.

Length of n-th row in the array of A207375, if n >= 1. - Omar E. Pol, Feb 27 2012

LINKS

Antti Karttunen, Table of n, a(n) for n = 0..65537

Index entries for sequences computed from exponents in factorization of n

FORMULA

From Omar E. Pol, Feb 10 2011: (Start)

a(n) = 2 - A010052(n).

a(n) = 1 + A049240(n), n >=1.

a(n) = A000005(n)-A161840(n), n >= 1.

(End)

MATHEMATICA

Array[2 - Boole[IntegerQ@ Sqrt@ #] &, 105, 0] (* Michael De Vlieger, Nov 03 2017 *)

CROSSREFS

Cf. A010052.

Cf. A000005, A049240, A161840.

Sequence in context: A233136 A106054 A275437 * A173642 A234305 A304094

Adjacent sequences:  A169692 A169693 A169694 * A169696 A169697 A169698

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane, Apr 15 2010

STATUS

approved

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Last modified August 20 06:54 EDT 2018. Contains 313909 sequences. (Running on oeis4.)