A193434 6*n/5 = (n written backwards), n > 0.

45, 495, 4545, 4995, 45045, 49995, 450045, 454545, 495495, 499995, 4500045, 4549545, 4950495, 4999995, 45000045, 45045045, 45454545, 45499545, 49500495, 49545495, 49954995, 49999995, 450000045, 450495045, 454504545, 454999545, 495000495, 495495495, 499504995

Offset: 1

Author

Arkadiusz Wesolowski, Aug 01 2011

Keywords

• base
• nonn

Examples

			495 belongs to this sequence because 6*495/5 = 594.
		

Links

• Ray Chandler, Table of n, a(n) for n = 1..10000 (first 4000 terms from Arkadiusz Wesolowski)

Crossrefs

Cf. A001232, A008918, A057148, A101705.

Programs

Mathematica

Rest@Select[FromDigits /@ Tuples[{0, 45}, 8], IntegerDigits[6*#/5] == Reverse@IntegerDigits[#] &] (* Arkadiusz Wesolowski, Aug 14 2012 *)

Python

def A193434(n):
    a = 1<<(m:=n+1).bit_length()-2
    s = bin(a|(m&a-1))[2:]
    return 45*int(s+(s[::-1] if a&m else s[-2::-1])) # Chai Wah Wu, Jul 23 2024

Formula

a(n) = 45*A057148(n+1). - Ray Chandler, Oct 09 2017