A043053 a(n) = (s(n) + 1)/5, where s(n) = n-th base-5 palindrome that starts with 4.

1, 5, 21, 22, 23, 24, 25, 101, 107, 113, 119, 125, 501, 506, 511, 516, 521, 527, 532, 537, 542, 547, 553, 558, 563, 568, 573, 579, 584, 589, 594, 599, 605, 610, 615, 620, 625, 2501, 2531, 2561, 2591, 2621, 2627, 2657, 2687, 2717

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..937 (all terms up to 5 million)

Mathematica

b5s4Q[n_]:=Module[{idn5=IntegerDigits[n, 5]}, idn5[[1]]==4&&idn5 == Reverse[ idn5]]; (#+1)/5&/@Select[Range[30000], b5s4Q] (* Harvey P. Dale, Jun 22 2022 *)

Crossrefs

Sequence in context: A355036 A263130 A165204 * A004163 A350328 A113410

Adjacent sequences: A043050 A043051 A043052 * A043054 A043055 A043056

Keyword

nonn,base

Author

Clark Kimberling

Status

approved