OFFSET
1,2
EXAMPLE
The sum of the first 12 terms of the sequence is 133 = 7*19.
There are 9 terms from among the first 12 terms of the sequence that are coprime to 133 (a(1)=1, a(2)=2, a(3)=4, a(5)=8, a(6)=10, a(7)=12, a(9)=16, a(10)=18, a(11)=20). So a(13)= a(12) + 9 = 30.
MAPLE
a[1] := 1; for n from 2 to 60 do ct := 0; for j to n-1 do if gcd(a[j], sum(a[i], i = 1 .. n-1)) = 1 then ct := ct+1 else ct := ct end if end do; a[n] := a[n-1]+ct end do; seq(a[n], n = 1 .. 60) # Emeric Deutsch, Jul 17 2007
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Jul 01 2007
EXTENSIONS
More terms from Emeric Deutsch and Joshua Zucker, Jul 17 2007
STATUS
approved