A193434 - OEIS

%I #42 Jul 23 2024 20:21:19

%S 45,495,4545,4995,45045,49995,450045,454545,495495,499995,4500045,

%T 4549545,4950495,4999995,45000045,45045045,45454545,45499545,49500495,

%U 49545495,49954995,49999995,450000045,450495045,454504545,454999545,495000495,495495495,499504995

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

%H Ray Chandler, <a href="/A193434/b193434.txt">Table of n, a(n) for n = 1..10000</a> (first 4000 terms from Arkadiusz Wesolowski)

%F a(n) = 45*A057148(n+1). - _Ray Chandler_, Oct 09 2017

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

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

%o (Python)

%o def A193434(n):

%o     a = 1<<(m:=n+1).bit_length()-2

%o     s = bin(a|(m&a-1))[2:]

%o     return 45*int(s+(s[::-1] if a&m else s[-2::-1])) # _Chai Wah Wu_, Jul 23 2024

%Y Cf. A001232, A008918, A057148, A101705.

%K base,nonn

%O 1,1

%A _Arkadiusz Wesolowski_, Aug 01 2011