

A253302


Smallest integer m such that gcd{x  sum of proper divisors of x is m} is equal to n, when there are at least two such x's.


1



1, 16, 300, 136, 50316, 186, 97748, 1352, 72318, 1340, 1652, 1356
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OFFSET

1,2


COMMENTS

Only integers m that satisfy A048138(m) > 1 are considered here.
Other known terms with odd indices: a(25)=39926, a(49)=46850.
For terms with even indices see A253303.


LINKS



EXAMPLE

For every prime p the sum of proper divisors of p is 1, and the GCD of the primes is 1, so a(1) = 1.


PROG

(PARI) build(nb) = {vs = vector(nb); nc = nb^2; forcomposite(n=2, nc, val = sigma(n)n; if (val <= nb, if (vs[val] == 0, vs[val] = n, vs[val] = gcd(vs[val], n)); ); ); vs[1] = 1; vs; }
lista() = {vd = build(100000); vmax = 20; vr = vector(vmax); for (ig=1, vmax, for (i=1, #vd, w = vd[i]; if (w ==ig, vr[ig] = i; break; ); ); ); for (i=1, #vr, if (vr[i] == 0, break, print1(vr[i], ", "))); }


CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



