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A064027 a(n) = (-1)^n*Sum_{d|n}(-1)^d*d^2. 2
1, 3, 10, 19, 26, 30, 50, 83, 91, 78, 122, 190, 170, 150, 260, 339, 290, 273, 362, 494, 500, 366, 530, 830, 651, 510, 820, 950, 842, 780, 962, 1363, 1220, 870, 1300, 1729, 1370, 1086, 1700, 2158, 1682, 1500, 1850, 2318, 2366, 1590, 2210, 3390, 2451, 1953 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

FORMULA

Multiplicative with a(2^e) = (4^(e+1)-7)/3, a(p^e) = (p^(2*e+2)-1)/(p^2-1), p > 2. a(n) = (-1)^n*(A001157(n)-2*A050999(n)).

CROSSREFS

Cf. A002129, A008457.

Sequence in context: A074178 A178996 A127852 * A028878 A010896 A135446

Adjacent sequences:  A064024 A064025 A064026 * A064028 A064029 A064030

KEYWORD

mult,nonn

AUTHOR

Vladeta Jovovic (vladeta(AT)eunet.rs), Sep 11 2001

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Last modified February 17 16:39 EST 2012. Contains 206058 sequences.