A158377 - OEIS

%I #7 Dec 26 2023 12:24:25

%S 0,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,

%T 27,28,29,10,31,32,33,34,35,36,37,38,39,40,41,14,43,44,45,46,47,48,49,

%U 50,51,52,53,54,55,56,57,58,59,15,61,62,63,64,65,22,67,68,69,14,71,72

%N a(1) = 0, a(n) = lcm(A034684(n), A034699(n)) for n >= 2.

%C a(n) for n >= 2 equals LCM of minimal and maximal prime power factors in prime factorization of n. For n >= 2 holds: a(n)*A100994(n) = A034684(n)*A034699(n). a(n) for n >= 2 it deviates from A000027(n), first different term is a(30)=a(2*3*5), a(30)=lcm(2,5)=10, A000027(30)= 30. Sequence of deviations from A000027(n): 30,42,60,66,70,78,84,90,...

%F a(1) = 0, a(p) = p, a(pq) = pq, a(pq...z) = pz, a(p^k) = p^k, for p = primes (A000040), pq = product of two distinct primes (A006881), pq...z = product of k (k > 2) distinct primes p, q, ..., z (A120944), p^k = prime powers (A000961(n) for n > 1), k = natural numbers (A000027).

%e For n = 30 = 2*3*5, a(30) = lcm(2,5) = 10.

%Y Cf. A100994, A034684, A034699, A000027.

%K nonn

%O 1,2

%A _Jaroslav Krizek_, Mar 17 2009