cp's OEIS Frontend

A290148 a(n) is the integer resulting from the concatenation of the unit digit of n-1 to the digits of n without its own unit digit.

%I A290148 #20 Feb 23 2025 08:57:06
%S A290148 0,1,2,3,4,5,6,7,8,91,1,11,21,31,41,51,61,71,81,92,2,12,22,32,42,52,
%T A290148 62,72,82,93,3,13,23,33,43,53,63,73,83,94,4,14,24,34,44,54,64,74,84,
%U A290148 95,5,15,25,35,45,55,65,75,85,96,6,16,26,36,46,56,66,76,86,97,7
%N A290148 a(n) is the integer resulting from the concatenation of the unit digit of n-1 to the digits of n without its own unit digit.
%C A290148 Take list of integers n >= 1, move the right-most digit of each term to the start of the next term.
%C A290148 Every number appears, see A381225. - _N. J. A. Sloane_, Feb 23 2025
%H A290148 Michael S. Branicky, <a href="/A290148/b290148.txt">Table of n, a(n) for n = 1..20000</a>
%F A290148 a(n) = (n-1 mod 10)*10^A004216(n) + floor(n/10). # _Robert Israel_, Jul 21 2017
%e A290148 For n=46, n-1 is 45, so a(46) is the concatenation of 5 (the unit digit of 45) and 4 (46 without 6), giving 54.
%e A290148 For n=123, n-1 is 122, so a(123) is the concatenation of 2 (the unit digit of 122) and 12 (123 without 3), giving 212.
%p A290148 f:= n -> (n-1 mod 10) * 10^ilog10(n) + floor(n/10);
%o A290148 (PARI) a(n) = my(precd = (n-1)%10); if (n < 10, precd, eval(concat(Str(precd), Str(n\10))));
%o A290148 (Python)
%o A290148 def a(n): return 0 if n == 1 else int(str((n-1)%10)+ str(n)[:-1])
%o A290148 print([a(n) for n in range(1, 72)]) # _Michael S. Branicky_, Feb 22 2025
%Y A290148 Cf. A004216, A032762, A381225.
%K A290148 nonn,base,look
%O A290148 1,3
%A A290148 _Michel Marcus_, Jul 21 2017