A248378 a(2n) = concatenation of n+1 with n+2, a(2n+1) = concatenation of n+2 with n+1.

12, 21, 23, 32, 34, 43, 45, 54, 56, 65, 67, 76, 78, 87, 89, 98, 910, 109, 1011, 1110, 1112, 1211, 1213, 1312, 1314, 1413, 1415, 1514, 1516, 1615, 1617, 1716, 1718, 1817, 1819, 1918, 1920, 2019, 2021, 2120, 2122, 2221, 2223, 2322, 2324, 2423, 2425, 2524, 2526

Offset: 0

Author

N. J. A. Sloane, Oct 07 2014

Keywords

• nonn
• base
• easy

References

• Charles Duvall, Email to N. J. A. Sloane, Oct 07 2014.

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A001704, A127423.

Cf. A154530 (primes).

Programs

Haskell

import Data.List (transpose)
a248378 n = a248378_list !! n
a248378_list = concat $ transpose [a001704_list, tail a127423_list]
-- Reinhard Zumkeller, Oct 07 2014

Mathematica

Table[{FromDigits[Join[IntegerDigits[n],IntegerDigits[n+1]]],FromDigits[Join[IntegerDigits[n+1],IntegerDigits[ n]]]},{n,30}]//Flatten (* Harvey P. Dale, Apr 19 2024 *)