

A065651


Sum_{k=1..n} (1)^tau(k)=n2*floor(sqrt(n)).


2



0, 1, 0, 1, 2, 3, 4, 3, 4, 5, 6, 7, 8, 9, 8, 9, 10, 11, 12, 13, 14, 15, 16, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59
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OFFSET

2,5


LINKS

Harry J. Smith, Table of n, a(n) for n=2,...,1000


MATHEMATICA

Table[n2*Floor[Sqrt[n]], {n, 2, 80}] (* Harvey P. Dale, Jul 27 2012 *)


PROG

(PARI) { for (n=2, 1000, a=n  2*sqrtint(n); write("b065651.txt", n, " ", a) ) } \\ Harry J. Smith, Oct 25 2009


CROSSREFS

Cf. A000196, A028391, A028392.
Sequence in context: A285872 A227181 A268233 * A221356 A177329 A253852
Adjacent sequences: A065648 A065649 A065650 * A065652 A065653 A065654


KEYWORD

nonn


AUTHOR

Vladeta Jovovic, Dec 03 2001


STATUS

approved



