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A096002
Let {b(n)} = A095996; then a(n) = number of terms {b(1),b(2),...,b(n-1)} which are coprime to n.
1
0, 1, 2, 2, 4, 2, 6, 4, 4, 3, 10, 3, 12, 4, 3, 8, 16, 4, 18, 4, 4, 6, 22, 5, 8, 7, 10, 5, 28, 2, 30, 16, 5, 9, 5, 7, 36, 10, 6, 6, 40, 3, 42, 7, 5, 12, 46, 9, 12, 7, 7, 8, 52, 10, 6, 7, 8, 15, 58, 3, 60, 16, 6, 32, 6, 3, 66, 10, 9, 3, 70, 13, 72, 19, 7, 11, 7, 4, 78, 10
OFFSET
1,3
LINKS
FORMULA
If p is prime, then a(p) = p-1.
MATHEMATICA
f[n_] := f[n] = Select[Divisors[n! ], GCD[ #, n] == 1 &][[ -1]]; Table[ Length[ Select[ Range[n - 1], GCD[ f[ # ], n] == 1 &]], {n, 2, 33}]
PROG
(PARI) seq(n)={my(v=vector(n, n, denominator(n^n/n!))); vector(n, n, sum(k=1, n-1, gcd(v[k], n)==1)); } \\ Andrew Howroyd, Nov 05 2019
CROSSREFS
Cf. A095996.
Sequence in context: A099735 A322352 A091279 * A082175 A129292 A126606
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jul 19 2004, based on a suggestion from Leroy Quet, Jun 18 2004
EXTENSIONS
a(33) - a(41) from Robert G. Wilson v, May 05 2013
a(1) corrected and terms a(42) and beyond from Andrew Howroyd, Nov 05 2019
STATUS
approved