A096217 a(n) = sum of terms of {a(1),a(2),a(3),...a(n-1)} which are coprime to n.

1, 1, 2, 2, 6, 2, 14, 2, 24, 2, 56, 2, 114, 2, 86, 2, 318, 2, 524, 2, 632, 2, 1798, 2, 3598, 2, 6736, 2, 12138, 2, 24278, 2, 37756, 2, 72308, 2, 160424, 2, 308250, 2, 629102, 2, 1258120, 2, 937358, 2, 3453688, 2, 3437884, 2, 9395312, 2, 18802902, 2, 36816688, 2

Offset

1,3

Comments

a(n) is 2 if n is an even integer >= 4.

a(7937) has more than 1000 decimal digits. - Chai Wah Wu, Aug 30 2014

Links

Chai Wah Wu, Table of n, a(n) for n = 1..7936

Example

a(1)=1, a(2)=1, a(3)=2, a(4)=2, a(6)=2, a(7)=14 and a(8)=2 are the terms, prior to a(9), which are coprime to 9. So a(9) = 1 +1 +2 +2 +2 +14 +2 = 24.

Mathematica

a[1] = 1; a[n_] := a[n] = Plus @@ (a /@ Select[Range[n - 1], GCD[ a[ # ], n] == 1 &]); Table[ a[n], {n, 56}] (* Robert G. Wilson v, Jul 31 2004 *)

Prog

(Python)
from gmpy2 import gcd
A096217 = [1]
for n in range(2, 10**4):
    A096217.append(sum(x for x in A096217 if gcd(x, n) == 1))
# Chai Wah Wu, Aug 30 2014

Crossrefs

Sequence in context: A071223 A249631 A055934 * A281145 A098555 A057562

Adjacent sequences: A096214 A096215 A096216 * A096218 A096219 A096220

Keyword

nonn

Author

Leroy Quet, Jul 28 2004

Extensions

Edited and extended by Robert G. Wilson v, Jul 31 2004

Status

approved