[seqfan] Array organizing natural numbers by the number of subsets of their proper divisors that sum to k=0 .. ?

Antti Karttunen antti.karttunen at gmail.com
Sun May 10 13:35:33 CEST 2015

Dear Seqfans,

Here is a suggestion for an array, where each row k gives all natural
numbers for which A065205(n) = k, for rows k=0..
(Where https://oeis.org/A065205 "Number of subsets of proper divisors
of n that sum to n.")

Hand-grepping from https://oeis.org/A065205/b065205.txt
I constructed the following north-west corner:

  1,  2,  3,  4,  5,  7,  8,  9,
  6, 20, 28, 78, 88,
 12, 18, 42, 56, 66,
 30, 40, 54,350,380,

Neither of its antidiagonal readings seem to be in OEIS.

The top row is https://oeis.org/A136447 (complement of pseudoperfect numbers)
second row https://oeis.org/A064771
third row https://oeis.org/A152615
fourth row https://oeis.org/A152616
(and the fifth row is not yet in OEIS)
the leftmost column is https://oeis.org/A096356

Assuming that each row contains an infinite number of terms (for each
k), would it make sense to submit this one? Any takers?

Best regards,


More information about the SeqFan mailing list