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A203616
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Numbers k such that the reversal of sigma*(k) equals the sum of the reversals of the anti-divisors of k, where sigma*(k) is the sum of the anti-divisors of k.
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2
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1, 2, 3, 4, 5, 6, 8, 9, 20, 63, 96, 97, 317, 596, 1473, 3934, 26777, 27684, 50867, 51767, 62417, 322001, 393216, 1308775, 1420260, 1851474, 2651867, 2659067, 3040656, 3227267, 3289277, 3376007, 4626917, 4639067, 5378507, 6054521, 6227027, 6239839, 6439067, 6581929
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OFFSET
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1,2
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COMMENTS
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A066466 is a subsequence of this sequence.
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LINKS
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EXAMPLE
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n=317. Anti-divisors: 2, 3, 5, 127, 211.
Sum of the reversals of the anti-divisors: 2+3+5+721+112=843.
Sigma*(317)=348 and its reversal is 843.
n=1473. Anti-divisors: 2, 5, 6, 7, 19, 31, 95, 155, 421, 589, 982.
Sum of the reversals of the anti-divisors:
2+5+6+7+91+13+59+551+124+985+289=2132.
Sigma*(1473)=2312 and its reversal is 2132.
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MAPLE
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isA203616:=proc(j) local a, b, c; a:=0; b:=0;
for c from 2 to j-1 do
if abs((j mod c)-c/2)<1 then a:=a+A004086(c); b:=b+c; fi;
od;
for n to 10^7 do if isA203616(n) then lprint(n) fi od: # simplified by M. F. Hasler, Jan 29 2012
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PROG
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(Python)
from itertools import count, islice
from sympy.ntheory.factor_ import antidivisors
def a203616():
isa = lambda n: str(sum((a:=antidivisors(n))))[::-1]==str(sum(map(int, (str(_)[::-1] for _ in a))))
yield from (n for n in count(1) if isa(n))
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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