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A074898 Impossible values for sum of anti-divisors of n. 2
1, 6, 7, 9, 11, 15, 17, 20, 21, 25, 26, 27, 29, 31, 33, 35, 37, 38, 43, 44, 45, 47, 49, 51, 53, 59, 61, 62, 63, 65, 67, 68, 69, 71, 73, 75, 77, 79, 81, 82, 83, 85, 87, 89, 91, 93, 95, 97, 99, 100, 103, 105, 109, 111, 113, 115, 117, 119, 120, 121, 123, 125, 127, 128, 129, 131, 133, 134, 135, 137, 139, 141, 143, 145, 146, 149, 151, 153, 155, 157, 158, 159, 161, 163, 165, 167, 168, 169, 170, 171 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

See A066272 for definition of anti-divisor.

Like A005114 but using anti-divisors. [Paolo P. Lava, Jul 06 2011]

LINKS

Paolo P. Lava, Table of n, a(n) for n = 1..10000

MAPLE

with(numtheory);

P:=proc(i)

local a, b, c, d, k, n, s, v;

v:=array(3..i); d:={};

for n from 1 to 24772 do d:=d union {n}; od;

for n from 3 by 1 to i do

  a:={};

   for k from 2 to n-1 do

     if abs((n mod k)- k/2) < 1 then a:=a union {k}; fi;

   od;

   b:=nops(a); c:=op(a); s:=0;

   if b>1 then

     for k from 1 to b do s:=s+c[k]; od;

   else s:=c;

   fi;

  v[n]:=s;

od;

a:={};

for n from 3 to i do a:=a union {v[n]}; od;

b:=d minus a; b:=sort([op(b)]);

end:

P(10000);

# Paolo P. Lava, Jul 06 2011

CROSSREFS

Cf. A005114, A066417.

Sequence in context: A022892 A120164 A335623 * A258153 A175221 A094010

Adjacent sequences:  A074895 A074896 A074897 * A074899 A074900 A074901

KEYWORD

nonn

AUTHOR

Jason Earls, Sep 14 2002

EXTENSIONS

More terms from Paolo P. Lava, Jul 06 2011

STATUS

approved

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Last modified November 29 04:38 EST 2021. Contains 349416 sequences. (Running on oeis4.)