A193431 Put the natural numbers together without spaces and read them three at a time advancing one space each time.

123, 234, 345, 456, 567, 678, 789, 891, 910, 101, 11, 111, 112, 121, 213, 131, 314, 141, 415, 151, 516, 161, 617, 171, 718, 181, 819, 192, 920, 202, 21, 212, 122, 222, 223, 232, 324, 242, 425, 252, 526, 262, 627, 272, 728, 282, 829, 293, 930, 303, 31, 313

Offset: 1

Author

Reinhard Zumkeller, Jul 28 2011

Keywords

• nonn
• base

Links

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

Crossrefs

Cf. A136414, A193492, A193493.

Programs

Haskell

a193431 n = a193431_list !! (n-1)
a193431_list = f a007376_list where
   f (x:xs'@(x':x'':xs)) = 10*(10*x + x') + x'' : f xs'

Mathematica

Module[{nn=50,d},d=Flatten[IntegerDigits/@Range[nn]];FromDigits/@ Partition[ d,3,1]] (* Harvey P. Dale, Nov 16 2021 *)

Formula

a(n) = 10 * (10 * A007376(n) + A007376(n+1)) + A007376(n+2).