A293542 a(1)=1; for n>1, a(n) = least integer greater than a(n-1) such that the sums of the divisors of the pairwise sums of a(1),...,a(n) are all distinct.

1, 2, 4, 8, 19, 28, 56, 72, 101, 144, 202, 240, 261, 448, 511, 602, 772, 806, 1152, 1296, 1541, 1602, 2016, 2256, 2900, 3322, 3362, 3978, 4376, 5887, 6416, 7702, 8228, 8578, 11341, 11382, 13376, 13692, 16083, 16380, 16544, 17382, 22726, 24944, 26302, 27508, 30580, 33184, 34020, 37474

Offset

1,2

Links

Logan J. Kleinwaks, Table of n, a(n) for n = 1..250

Example

Let s(n) be the sum of the divisors of n. a(3)!=3 because s(1+3)=s(2+2)=7. a(3)=4 because s(1+1)=3, s(1+2)=4, s(1+4)=6, s(2+2)=7, s(2+4)=12, and s(4,4)=15 are all distinct.

Crossrefs

Cf. A000203, A293541, A005282.

Sequence in context: A058374 A007881 A367441 * A049960 A018306 A139784

Adjacent sequences: A293539 A293540 A293541 * A293543 A293544 A293545

Keyword

nonn

Author

Logan J. Kleinwaks, Oct 11 2017

Status

approved