A019273 First run of n consecutive integers with same number of divisors ends at a(n).

1, 3, 35, 245, 11609, 28379, 171899, 1043710445728, 2197379769828, 2642166652554084

Offset: 1

Author

Jud McCranie

Keywords

• nonn
• hard

Comments

The entry 40315 given in Guy and Wells is incorrect.

Terminating number in the sequence of consecutive integers with the same number of divisors in A006558. - Jud McCranie, Jan 14 2006

Examples

			phi(33)=phi(34)=phi(35), so a(3)=35
		

References

• R. K. Guy "Unsolved Problems in Number Theory", section B18.
• David Wells "Dictionary of Curious and Interesting Numbers" #40311.

Crossrefs

Cf. A000005, A005237, A005238, A006601, A049051, A006558, A039665.

a(n)=A006558(n)+n-1.

Extensions

More terms from Jud McCranie, Oct 04 2002

One more term from Jud McCranie, Jan 14 2006

a(10) by Jud McCranie, Nov 27 2018