Divide each term by 6: 1, 2, 4, 8...
The sequence is powers of 2 starting at zero.
2^x for x≥0 generates each term of the reduced series, so the given series would be 6(2^x).
If x starts at 1 instead of zero, the series is generated by 6(2^(x-1)) or 6(2ˣ⁻¹) which looks like answer D.
