A295430 a(n) is the least nontrivial multiple of n that begins with 3.

3, 30, 30, 32, 30, 30, 35, 32, 36, 30, 33, 36, 39, 308, 30, 32, 34, 36, 38, 300, 315, 308, 322, 312, 300, 312, 324, 308, 319, 300, 310, 320, 330, 306, 315, 324, 333, 304, 312, 320, 328, 336, 301, 308, 315, 322, 329, 336, 343, 300, 306, 312, 318, 324, 330, 336, 342, 348, 354, 300, 305, 310, 315

Offset: 1

Author

Robert Israel, Feb 12 2018

Keywords

• nonn

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A082792.

Programs

Maple

f:= proc(n) local m,k;
  for m from 0 do
    k := max(2, ceil(3*10^m/n));
    if k*n < 4*10^m then return k*n end if
  end do
end proc:
seq(f(i),i=1..100);

PARI

a(n) = {my(k=2); while(digits(k*n)[1] != 3, k++); k*n;} \\ Michel Marcus, Feb 13 2018

Python

def A295430(n):
    m = 2*n
    while True:
        if str(m)[0] == '3':
            return m
        m += n # Chai Wah Wu, Feb 13 2018