A122640 a(n) = {2n}_n.

2, 4, 6, 8, 5, 8, 11, 14, 17, 20, 24, 28, 32, 36, 45, 50, 55, 60, 65, 80, 86, 92, 98, 104, 125, 132, 139, 146, 153, 180, 188, 196, 204, 212, 245, 254, 263, 272, 281, 320, 330, 340, 350, 360, 405, 416, 427, 438, 449, 2500, 2603, 2708, 2815, 2924, 3080, 3194, 3310, 3428, 3548

Offset: 1

Author

N. J. A. Sloane, Sep 21 2006

Keywords

• nonn
• base
• easy

Comments

See A122618 for notation.

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A122618 (n_n).

Programs

Maple

a:= n-> (l-> add(l[i]*n^(i-1), i=1..nops(l)))(convert(2*n, base, 10)):
seq(a(n), n=1..60);  # Alois P. Heinz, Jul 04 2022

Mathematica

Array[FromDigits[IntegerDigits[2 #], #] &, 59] (* Michael De Vlieger, Jul 04 2022 *)

PARI

a(n) = fromdigits(digits(2*n),max(2,n)); \\ Kevin Ryde, Jul 04 2022