A028899 Map n = Sum c_i 10^i to a(n) = Sum c_i 4^i.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 28, 29, 30, 31, 32, 33

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• base
• look

Links

• Robert Israel, Table of n, a(n) for n = 0..10000

Programs

Maple

f:= proc(n) option remember;
n mod 10 + 4*procname(floor(n/10))
end proc:
f(0):= 0:
map(f, [$0..100]); # Robert Israel, Jun 11 2018

Formula

From Robert Israel, Jun 11 2018: (Start)

a(i+10*j) = i + 4*a(j) for 0 <= i <= 9.

G.f. g(x) satisfies g(x) = (x+2*x^2+...+9*x^9)/(1-x^10) + 4*(1-x^10)*g(x^10)/(1-x). (End)

Extensions

More terms from Erich Friedman.