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

1,1

Links

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

Formula

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

Mathematica

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

Prog

(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'

Crossrefs

Cf. A136414, A193492, A193493.

Sequence in context: A153254 A360639 A227522 * A306643 A303241 A004945

Adjacent sequences: A193428 A193429 A193430 * A193432 A193433 A193434

Keyword

nonn,base

Author

Reinhard Zumkeller, Jul 28 2011

Status

approved