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A241004
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Numbers n such that anti-phi(sigma*(n)) = n, where anti-phi is A066452 and sigma* is the sum of anti-divisors of n (A066417).
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0
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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90 is in the sequence: Anti-divisors of 90 are 4, 12, 20, 36, 60 and their sum is 132. Anti-phi of 132 is 90.
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MAPLE
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isA241004 := proc(n)
end proc:
for n from 1 do
if isA241004(n) then
printf("%d\n", n) ;
end if;
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PROG
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(PARI) sad(n) = my(k); if(n>1, k=valuation(n, 2); sigma(2*n+1)+sigma(2*n-1)+sigma(n/2^k)*2^(k+1)-6*n-2, 0);
antidiv(n) = {my(v = []); for (k=2, n-1, if (abs((n % k) - k/2) < 1, v = concat(v, k)); ); v; }
antiphi(n) = {my(vad = antidiv(n)); my(nbad = 0); for (j=1, n-1, isad = 1; for (k=1, #vad, if ((j % vad[k]) == 0, isad = 0; break); ); nbad += isad; ); nbad; }
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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