A330336 A322131/2.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 105, 106, 107, 108, 109, 20, 21, 22, 23, 24, 205, 206, 207, 208, 209, 30, 31, 32, 33, 34, 305, 306, 307, 308, 309, 40, 41, 42, 43, 44, 405, 406, 407, 408, 409, 50, 51, 52, 53, 54, 505, 506, 507

Offset: 0

Author

N. J. A. Sloane, Dec 17 2019

Keywords

• nonn
• base

Links

• Rémy Sigrist, Table of n, a(n) for n = 0..10000

Crossrefs

Cf. A322131.

Programs

Maple

a:= n-> (s-> parse(cat(seq(parse(s[i])*2, i=1..length(s))))/2)(""||n):
seq(a(n), n=0..70);  # Alois P. Heinz, Dec 18 2019

PARI

a(n, base=10) = my (d=digits(n, base), v=0); for (i=1, #d, v = v*base^max(1, #digits(2*d[i], base)) + 2*d[i]); v/2 \\ Rémy Sigrist, Dec 18 2019

Formula

a(n) >= n with equality iff all the digits of the decimal representation of n, except possibly the first one, are in the range 0...4. - Rémy Sigrist, Dec 18 2019