A138841 Concatenation of initial and final digit of n-th Mersenne prime A000668(n).

33, 77, 31, 17, 81, 11, 57, 27, 21, 61, 17, 17, 61, 57, 17, 17, 41, 21, 11, 27, 41, 31, 21, 41, 41, 41, 81, 57, 57, 51, 77, 17, 11, 47, 81, 61, 11, 41, 91, 17, 27, 17, 31, 11, 27, 11, 31

Offset: 1

Author

Omar E. Pol, Apr 01 2008

Keywords

• base
• nonn
• more
• less

Examples

			a(5)=81 because the 5th Mersenne prime is 8191, A000668(5)=8191.
		

Crossrefs

Cf. A000668, A073729, A080172, A135613, A138840, A138842, A138843.

Formula

a(n) = A073729(A000668(n)). - Michel Marcus, Apr 17 2018

Extensions

a(40)-a(47) from Ivan Panchenko, Apr 17 2018