1,1

Q_k the k-th primorial number (A002110) is the smallest positive integer such that its number of unitary divisors (A034444) is 2^k. Thus the binary orders (A029837) of primorial numbers (A045716) determines the maximal values of unitary divisors in binary order ranges.

2^k occurs in the sequence g(Q_k) - g(Q_k-1)+1 times, where g is binary order and Q_k is the k-th primorial number

128 occurs in the sequence from index 19 and 23 inclusively (5 times) because the 7th primorial number Q_7=510510 has binary order 19 and Q_8, the next one is 9699690 has binary order 24 (it is between 2^23 and 2^24).

Cf. A029837, A034444, A002110, A045716.

Sequence in context: A100835 A120541 A059867 this_sequence A051754 A108747 A116931

Adjacent sequences: A046968 A046969 A046970 this_sequence A046972 A046973 A046974

nonn

Labos E. (labos(AT)ana.sote.hu)