a(1)=0=0_6=0_7
a(2)=1=1_6=1_7
a(3)=2=2_6=2_7
a(4)=3=3_6=3_7
a(5)=4=4_6=4_7
a(6)=5=5_6=5_7
a(7)=8=12_6=11_7
a(8)=9=13_6=12_7
a(9)=10=14_6=13_7
a(10)=11=15_6=14_7
a(11)=16=24_6=22_7
a(12)=17=25_6=23_7
a(13)=57=133_6=111_7
a(14)=58=134_6=112_7
a(15)=59=135_6=113_7
a(16)=65=145_6=122_7
a(17)=89=225_6=155_7
a(18)=130=334_6=244_7
a(19)=131=335_6=245_7
a(20)=172=444_6=334_7
a(21)=173=445=335=7
a(22)=179=455_6=344_7
a(23)=1600=11224_6=4444_7
a(24)=1601=11225_6=4445_7
a(25)=3203=22455_6=12224_7