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.

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, 62, 72, 82, 93, 3, 13, 23, 33, 43, 53, 63, 73, 83, 94, 4, 14, 24, 34, 44, 54, 64, 74, 84, 95, 5, 15, 25, 35, 45, 55, 65, 75, 85, 96, 6, 16, 26, 36, 46, 56, 66, 76, 86, 97, 7

Offset

1,3

Comments

Take list of integers n >= 1, move the right-most digit of each term to the start of the next term.

Every number appears, see A381225. - N. J. A. Sloane, Feb 23 2025

Links

Michael S. Branicky, Table of n, a(n) for n = 1..20000

Formula

a(n) = (n-1 mod 10)*10^A004216(n) + floor(n/10). # Robert Israel, Jul 21 2017

Example

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.
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.

Maple

f:= n -> (n-1 mod 10) * 10^ilog10(n) + floor(n/10);

Prog

(PARI) a(n) = my(precd = (n-1)%10); if (n < 10, precd, eval(concat(Str(precd), Str(n\10))));
(Python)
def a(n): return 0 if n == 1 else int(str((n-1)%10)+ str(n)[:-1])
print([a(n) for n in range(1, 72)]) # Michael S. Branicky, Feb 22 2025

Crossrefs

Cf. A004216, A032762, A381225.

Sequence in context: A331879 A098755 A028430 * A392618 A171717 A303369

Adjacent sequences: A290145 A290146 A290147 * A290149 A290150 A290151

Keyword

nonn,base,look

Author

Michel Marcus, Jul 21 2017

Status

approved