OFFSET
1,1
COMMENTS
If p is an odd prime then 2^(4*p - 2) * p is a term, hence this sequence is infinite.
Since A074206(k) depends only on the prime signature (A124010) of k, then each term is of the form A050324(k)/2 = A074206(A025487(k))/2.
Besides terms of the form 2^(4*p - 2) * p at least 79 terms not of this form are known. For example, 1115414963960152064 = 2^46 * 11^2 * 131 is a term not of this form. To ease the search, can we narrow the possible prime signatures of terms?
LINKS
EXAMPLE
3072 is a term since A074206(3072) = 6144 = 2 * 3072.
MATHEMATICA
h[1] = 1; h[n_] := h[n] = DivisorSum[n, h[#] &, # < n &]; Select[Range[1.5*10^6], h[#] == 2*# &]
PROG
(PARI) is(n) = A074206(n) == n<<1
CROSSREFS
KEYWORD
nonn,more
AUTHOR
David A. Corneth and Amiram Eldar, Apr 20 2020
STATUS
approved