OFFSET
1,2
EXAMPLE
8 = 1 + 7 is the sum of the divisors of 7. 1,3,5,7,9,11,13,15,17,19,21...are the positive integers which are coprime to 8. Of these integers, 13 is the 7th. So a(7) = 13.
MATHEMATICA
f[n_] := Block[{c = n, k = 0}, While[c > 0, k++; While[GCD[DivisorSigma[1, n], k] > 1, k++ ]; c-- ]; k ]; Table[f[n], {n, 63}] (* Ray Chandler, Aug 29 2006 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Leroy Quet, Aug 26 2006
EXTENSIONS
Extended by Ray Chandler, Aug 29 2006
STATUS
approved