A136414 Put the natural numbers together without spaces and read them two at a time advancing one space each time.

12, 23, 34, 45, 56, 67, 78, 89, 91, 10, 1, 11, 11, 12, 21, 13, 31, 14, 41, 15, 51, 16, 61, 17, 71, 18, 81, 19, 92, 20, 2, 21, 12, 22, 22, 23, 32, 24, 42, 25, 52, 26, 62, 27, 72, 28, 82, 29, 93, 30, 3, 31, 13, 32, 23, 33, 33, 34, 43, 35, 53, 36, 63, 37, 73, 38, 83, 39, 94, 40, 4, 41, 14

Offset: 1

Author

Ben Paul Thurston, Mar 31 2008

Keywords

• easy
• nonn
• base
• look

Comments

a(n) = A162711(n,2) for n>1. - Reinhard Zumkeller, Jul 11 2009

Examples

			34 is the third entry because the natural numbers written together look like 1234567891011 and reading them off two at a time produces 12, 23, 34, ...
		

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A001704, A193431, A193492, A193493.

Programs

Haskell

a136414 n = a136414_list !! (n-1)
a136414_list = zipWith (+) (tail a007376_list) $ map (10 *) a007376_list
-- Reinhard Zumkeller, Jul 28 2011

Formula

a(n) = 10*A007376(n) + A007376(n+1). - Reinhard Zumkeller, Jul 11 2009

Extensions

More terms from Reinhard Zumkeller, Jul 11 2009