A329062 -id:A329062 - cp's OEIS frontend

A328925 a(n) = A002322(n)/A118106(n); write n = Product_{i=1..t} p_i^e_i, then a(n) = A002322(n)/(lcm_{1<=i,j<=t,i!=j} ord(p_i,p_j^e_j)), where ord(a,r) is the multiplicative order of a modulo r, and A002322 is the Carmichael lambda (usually written as psi).

1, 1, 2, 2, 4, 1, 6, 2, 6, 1, 10, 1, 12, 2, 1, 4, 16, 1, 18, 1, 1, 1, 22, 1, 20, 1, 18, 1, 28, 1, 30, 8, 1, 2, 1, 1, 36, 1, 4, 1, 40, 1, 42, 1, 1, 2, 46, 1, 42, 1, 1, 1, 52, 1, 4, 1, 1, 1, 58, 1, 60, 6, 1, 16, 3, 1, 66, 2, 1, 1, 70, 1, 72, 1, 1, 1, 1, 1, 78, 1, 54, 2, 82, 1, 1, 3, 1

Offset: 1

Jianing Song, Oct 31 2019

nonn

It is easy to see that A118106(n) divides psi(n) = A002322(n).

If n = p^e for prime p, then A118106(p^e) = 1, so a(p^e) = A002322(p^e). The other n's such that a(n) > 1 are listed in A329062.

			A002322(14) = 6, while A118106(14) = 3, so a(14) = 2.

Cf. A002322, A118106, A328926 (indices of 1), A329062.

a(n) = A002322(n)/A118106(n) \\ See A002322 and A118106 for their programs

A328926 Numbers k such that A328925(k) = 1; numbers k such that if we write k = Product_{i=1..t} p_i^e_i, then lcm_{1<=i,j<=t,i!=j} ord(p_i,p_j^e_j) = A002322(k), where ord(a,r) is the multiplicative order of a modulo r, and A002322 is the Carmichael lambda (usually written as psi).

Original entry on oeis.org

1, 2, 6, 10, 12, 15, 18, 20, 21, 22, 24, 26, 28, 30, 33, 35, 36, 38, 40, 42, 44, 45, 48, 50, 51, 52, 54, 56, 57, 58, 60, 63, 66, 69, 70, 72, 74, 75, 76, 77, 78, 80, 84, 85, 87, 88, 90, 91, 92, 93, 96, 99, 100, 102, 104, 105, 106, 108, 110, 114, 115, 116, 118, 119, 120, 122

Offset: 1

Jianing Song, Oct 31 2019

nonn

Numbers such that A118106(k) = A002322(k).
{a(n)} intersect A000961 = {1, 2}.
{a(n)} union A329062 = N* \ A000961 U {1, 2}.
If k = Product_{i=1..t} p_i^e_i (t > 1), where {p_i} are primes such that p_i is a lambda primitive root modulo p_j^e_j for all i != j (that is to say, ord(p_i,p_j^e_j) = A002322(p_j^e_j), where ord(a,r) is the multiplicative order of a modulo r), then k is here, as A118106(k) = A002322(k). For example, k = 2^5 * 5 * 13.

			For k = 115 = 5 * 23, A118106(115) = lcm(ord(23,5),ord(5,23)) = lcm(4,22) = 44 = A002322(115), so 115 is a term.
For k = 973 = 7 * 139, A118106(973) = lcm(ord(139,7),ord(7,139)) = lcm(6,69) = 138 = A002322(973), so 973 is a term.

Cf. A118106, A002322, A326925, A329062, A000961.

isA328926(n) = (A002322(n) == A118106(n)) \\ See A002322 and A118106 for their programs

cp's OEIS Frontend

A328925 a(n) = A002322(n)/A118106(n); write n = Product_{i=1..t} p_i^e_i, then a(n) = A002322(n)/(lcm_{1<=i,j<=t,i!=j} ord(p_i,p_j^e_j)), where ord(a,r) is the multiplicative order of a modulo r, and A002322 is the Carmichael lambda (usually written as psi).

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