A083812 Numbers k such that 4*k-1 is the digit reversal of k-1.

18, 198, 1998, 19998, 178218, 199998, 1780218, 1999998, 17800218, 19782198, 19999998, 178000218, 197802198, 199999998, 1780000218, 1782178218, 1978002198, 1997821998, 1999999998, 17800000218, 17821978218, 19780002198, 19978021998, 19999999998, 178000000218, 178021780218, 178219978218

Offset

1,1

Comments

Each term has the first digit 1 and the last digit 8. - Stefano Spezia, Sep 18 2025

Links

Table of n, a(n) for n=1..27.

Example

18 - 1 = 17 and 4*18 - 1 = 71 = A004086(17);
198 - 1 = 197 and 4*198 - 1 = 791 = A004086(197);
178218 - 1 = 178217 and 4*178218 - 1 = 712871 = A004086(178217).

Mathematica

Select[Range[10^6], IntegerReverse[#-1]==4#-1 &] (* Stefano Spezia, Sep 18 2025 *)

Prog

(PARI) isok(k) = Vecrev(digits(4*k-1)) == digits(k-1); \\ Michel Marcus, Sep 23 2025

Crossrefs

Cf. A004086, A083811.

Except the 1st term 0, A086573 is a subsequence.

Sequence in context: A060532 A073397 A020920 * A086573 A097515 A177358

Adjacent sequences: A083809 A083810 A083811 * A083813 A083814 A083815

Keyword

nonn,base

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 08 2003

Extensions

Corrected by Stefano Spezia, Sep 18 2025 at the suggestion of David Radcliffe

Status

approved