A071686
Smallest solution to gcd(x, Rev(x)) = 2^n.
Original entry on oeis.org
2, 4, 8, 2192, 21920, 291008, 610688, 2112256, 2131456, 2937856, 25329664, 230465536, 694018048, 2344321024, 4688642048, 2112421888, 65012891648, 650128916480, 4494196736, 63769149440, 637691494400, 23842827272192, 276298064723968, 420127895977984, 4897795987210240
Offset: 1
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a[n_] := Block[{k = 2^n}, While[GCD[k, FromDigits@ Reverse@ IntegerDigits@ k] != 2^n, k += 2^n]; k]; Array[a, 17] (* Giovanni Resta, Nov 14 2019 *)
A072005
Smallest solution to gcd(k, reverse(k)) = 3^n.
Original entry on oeis.org
1, 3, 9, 2889, 2899999989, 4899999987, 19899999972, 29898999693, 49989958299, 49999917897, 99884394999, 372797889885, 1989767716659, 2678052898989, 17902896898419, 137530987695297, 189281899170567, 368055404997498, 14048104419899757, 437893473401621955, 218264275944702783
Offset: 0
n=4: 3^4 = 81, a(4) = 2899999989 = 3*3*3*3*35802469, reverse(a(4)) = 2*3*3*3*3*61111111; gcd = 81 = 3^n.
A072021
Smallest solution to gcd(x, reverse(x)) = 5^n.
Original entry on oeis.org
5, 5200, 521000, 5213750, 521875, 5218750, 52130234375, 5734841796875, 57869714843750, 526046650390625, 5265674365234375, 52187008544921875, 526515306396484375, 5213023309008789062500, 5213596736358642578125, 5260466086273193359375, 526041911745452880859375
Offset: 1
For n = 4, gcd(521875, 578125) = 3125 = 5^4.
For n = 8, a(8) = 5734841796875 = 5^9*2936239, reverse(a(8)) = 5786971484375 = 5^8*71*208657.
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a(n) = {my(k = 1); while (gcd(k, fromdigits(Vecrev(digits(k)))) != 5^n, k++); k;} \\ Michel Marcus, Jul 13 2018
A072051
Smallest k such that gcd(k, reverse(k)) = 11^n.
Original entry on oeis.org
11, 121, 1331, 14641, 121110352, 1332213872, 105923336431682, 4676049710123077, 36606937477221265, 30983951005022964839, 1365869521861436622239
Offset: 1
a(8) = 4676049710123077 = (11^8)*13*1678009, reverse(a(8)) = 7703210179406764 = (11^8)*2*2*157*57223.
Showing 1-4 of 4 results.