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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.
2
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
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
KEYWORD
nonn
AUTHOR
Logan J. Kleinwaks, Oct 11 2017
STATUS
approved