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A001704 a(n) = concatenation {n,n+1}. 21
12, 23, 34, 45, 56, 67, 78, 89, 910, 1011, 1112, 1213, 1314, 1415, 1516, 1617, 1718, 1819, 1920, 2021, 2122, 2223, 2324, 2425, 2526, 2627, 2728, 2829, 2930, 3031, 3132, 3233, 3334, 3435, 3536, 3637, 3738, 3839, 3940, 4041, 4142, 4243, 4344, 4445, 4546 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

A010051(a(A030457(n))) = 1. - Reinhard Zumkeller, Jun 27 2015

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = n*10^(1 + floor(log(n+1))) + n + 1, with n >= 1. - Paolo P. Lava, May 09 2008

MAPLE

P:=proc(n) local a, i; for i from 1 by 1 to n do a:=i*10^(1+floor(evalf(log10(i+1), 10)))+i+1; print(a); od; end: P(100); # Paolo P. Lava, May 09 2008

f:=proc(i) i*10^(1+floor(evalf(log10(i+1), 10)))+i+1; end: # gives a(n) - N. J. A. Sloane, Aug 04 2012

MATHEMATICA

f[n_] := FromDigits@Flatten@IntegerDigits[{n, n+1}]; Table[f[n], {n, 100}] (* T. D. Noe, Aug 09 2012 *)

PROG

(Haskell)

a001704 n = a001704_list !! (n-1)

a001704_list = map read (zipWith (++) iss $ tail iss) :: [Integer]

               where iss = map show [1..]

-- Reinhard Zumkeller, Oct 07 2014

(PARI) a(n)=eval(Str(n, n+1)) \\ Charles R Greathouse IV, Jul 23 2016

CROSSREFS

See A127421 for another version.

Cf. A215027, A248378, A030457, A010051.

Sequence in context: A072485 A035333 * A127421 A112131 A233032 A088997

Adjacent sequences:  A001701 A001702 A001703 * A001705 A001706 A001707

KEYWORD

nonn,base,easy

AUTHOR

N. J. A. Sloane

EXTENSIONS

More terms from Joshua Zucker and Jon E. Schoenfield, May 15 2007

STATUS

approved

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Last modified September 20 08:54 EDT 2017. Contains 292261 sequences.