A090959 Index of primorial(n) in A090958.

2, 4, 12, 41, 173, 679, 2806, 11221, 46200, 195762, 797388, 3338052, 13821332, 56256665, 230808795

Offset

1,1

Comments

Significance: a(n+1)-1 is the count of numbers < primorial(n+1) whose largest prime divisor is <= prime(n). E.g., a(5) = 39 is the index of 210=2*3*5*7 in A090958, which means there are 38 numbers of the form 2^a*3^b*5^c < 210. Can someone derive a general formula (asymptotic)?

Links

Table of n, a(n) for n=1..15.

Crossrefs

Cf. A090958.

Sequence in context: A218144 A222919 A264760 * A244035 A340025 A126942

Adjacent sequences: A090956 A090957 A090958 * A090960 A090961 A090962

Keyword

more,nonn

Author

Amarnath Murthy, Dec 31 2003

Extensions

Corrected and extended by David Wasserman, Feb 23 2006

Status

approved