A030655 Pair up the numbers.

12, 34, 56, 78, 910, 1112, 1314, 1516, 1718, 1920, 2122, 2324, 2526, 2728, 2930, 3132, 3334, 3536, 3738, 3940, 4142, 4344, 4546, 4748, 4950, 5152, 5354, 5556, 5758, 5960, 6162, 6364, 6566, 6768, 6970, 7172, 7374, 7576, 7778, 7980, 8182, 8384, 8586

Offset: 1

Author

Maghraoui Abdelkader

Keywords

• base
• nonn
• easy

Comments

That is, a(n) is the concatenation of 2n-1 and 2n. - Charles R Greathouse IV, Aug 07 2012

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A030656.

Subsequence of A005843.

Programs

Magma

[Seqint(Intseq(n+1) cat Intseq(n)): n in [1..86 by 2]];  // Bruno Berselli, Jun 18 2011

Mathematica

FromDigits[Flatten[IntegerDigits/@{#}]]&/@Partition[Range[90],2] (* Harvey P. Dale, Sep 28 2011 *)

PARI

a(n)=eval(concat(Str(2*n-1),2*n)) \\ Charles R Greathouse IV, Jun 18 2011

Extensions

More terms from Erich Friedman.