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

1,1

Comments

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

Links

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

Formula

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

Example

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, ...

Prog

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

Crossrefs

Cf. A001704, A193431, A193492, A193493.

Sequence in context: A346508 A104340 A367362 * A017401 A004960 A098953

Adjacent sequences: A136411 A136412 A136413 * A136415 A136416 A136417

Keyword

easy,nonn,base,look

Author

Ben Paul Thurston, Mar 31 2008

Extensions

More terms from Reinhard Zumkeller, Jul 11 2009

Status

approved