A354719 Replace each even digit in n with the digit to its left.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 11, 11, 13, 11, 15, 11, 17, 11, 19, 2, 11, 22, 33, 42, 55, 62, 77, 82, 99, 33, 31, 33, 33, 33, 35, 33, 37, 33, 39, 4, 11, 24, 33, 44, 55, 64, 77, 84, 99, 55, 51, 55, 53, 55, 55, 55, 57, 55, 59, 6, 11, 26, 33, 46, 55, 66, 77

Offset: 0

Author

Gavin Lupo, Jun 03 2022

Keywords

• nonn
• base
• easy
• look
• hear

Comments

If the leftmost digit in n is even, wrap around and replace it with the rightmost digit in n (see example).

Examples

			n    =  4 2 7 8 1
        ^ ^   ^      even digits,
a(n) =  1 4 7 7 1    to their left in n
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 0..10000
• Gavin Lupo, Logarithmic scatterplot of (n, a(n)) for n = 1..10000

Crossrefs

Cf. A139337, A348179, A349422.

Programs

Mathematica

Array[FromDigits@ Map[If[EvenQ@ #1, #2, #1] & @@ # &, Transpose@ {#, RotateRight[#, 1]}] &@ IntegerDigits[#] &, 67] (* Michael De Vlieger, Jun 19 2022 *)

PARI

prec(d, k) = k--; if (! k, k = #d); k;
a(n) = my(d=digits(n), v=d); for (k=1, #d, if (!(d[k] % 2), v[k] = d[prec(d,k)])); fromdigits(v); \\ Michel Marcus, Jun 04 2022

Python

def a(n):
    digits = list(map(int, str(n)))
    out = (d if d%2 else digits[i-1] for i, d in enumerate(digits))
    return int("".join(map(str, out)))
print([a(n) for n in range(68)]) # Michael S. Branicky, Jun 04 2022