A122213 a(n) = (sum of the divisors of n)th integer from among those positive integers which are coprime to n.

1, 5, 5, 13, 7, 35, 9, 29, 19, 43, 13, 83, 15, 55, 44, 61, 19, 115, 21, 103, 55, 79, 25, 179, 38, 89, 59, 129, 31, 269, 33, 125, 79, 113, 69, 271, 39, 125, 89, 223, 43, 335, 45, 183, 146, 149, 49, 371, 66, 231, 113, 211, 55, 359, 98, 279, 125, 185, 61, 629, 63, 197, 181

Offset

1,2

Links

Table of n, a(n) for n=1..63.

Example

8 = 1 + 7 is the sum of the divisors of 7. 1,2,3,4,5,6,8,9,10,11,12,13,15,16,... are the positive integers
which are coprime to 7. Of these integers, 9 is the 8th. So a(7) = 9.

Mathematica

f[n_] := Block[{c = DivisorSigma[1, n], k = 0}, While[c > 0, k++; While[GCD[n, k] > 1, k++ ]; c-- ]; k ]; Table[f[n], {n, 63}] (* Ray Chandler, Aug 29 2006 *)

Crossrefs

Cf. A122212.

Sequence in context: A370297 A339947 A206553 * A224067 A049735 A055526

Adjacent sequences: A122210 A122211 A122212 * A122214 A122215 A122216

Keyword

nonn

Author

Leroy Quet, Aug 26 2006

Extensions

Extended by Ray Chandler, Aug 29 2006

Status

approved