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Search: id:A145396
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| A145396 |
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a(n) = Sum_{d|n} sigma(d) + 3*Sum_{2c|n} sigma(c). |
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+0
1
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| 1, 7, 5, 23, 7, 35, 9, 59, 18, 49, 13, 115, 15, 63, 35, 135, 19, 126, 21, 161, 45, 91, 25, 295, 38, 105, 58, 207, 31, 245, 33, 291, 65, 133, 63, 414, 39, 147, 75, 413, 43, 315, 45, 299, 126, 175, 49, 675, 66, 266, 95, 345, 55, 406, 91, 531, 105, 217, 61, 805, 63, 231, 162, 607
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OFFSET
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1,2
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REFERENCES
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J. S. Rutherford, The enumeration and symmetry-significant properties of derivative lattices, Acta Cryst. A48 (1992), 500-508. See Table 1.
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MAPLE
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with(numtheory);
g:=proc(n)
local d, c, b, t0, t1, t2, t3;
t1:=divisors(n);
t0:=add( sigma(d), d in t1);
t2:=0;
for d in t1 do if d mod 2 = 0 then t2:=t2+sigma(d/2); fi; od:
t0+3*t2;
end;
[seq(g(n), n=1..100)];
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CROSSREFS
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Sequence in context: A064024 A140657 A078747 this_sequence A120404 A146619 A059990
Adjacent sequences: A145393 A145394 A145395 this_sequence A145397 A145398 A145399
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), Mar 13 2009
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