cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

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

Views

Author

Labos Elemer, Jun 03 2002

Keywords

Crossrefs

Programs

  • Mathematica
    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 *)

Formula

a(n) = A069554(2^n).

Extensions

a(22)-a(25) from Giovanni Resta, Oct 29 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

Views

Author

Labos Elemer, Jun 04 2002

Keywords

Examples

			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.
		

Crossrefs

Formula

a(n) = A069554(3^n).

Extensions

a(15)-a(20) from Giovanni Resta, Oct 30 2019

A072050 Smallest solution to GCD(x,A004086(x))=7^n.

Original entry on oeis.org

7, 18718, 343, 125204947, 231012215, 11298657013, 211066659013, 117088913464607, 2846847905744815, 108244538579770418, 2080795357577501075, 18312871825384462928, 26268977180287044053417, 1734582041294009627423816
Offset: 1

Views

Author

Labos Elemer, Jun 10 2002

Keywords

Crossrefs

Programs

Formula

a(n) = A069554(7^n).

Extensions

a(8)-a(9) from Max Alekseyev, Jun 17 2011
a(10)-a(14) from Giovanni Resta, Oct 30 2019

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

Views

Author

Labos Elemer, Jun 10 2002

Keywords

Examples

			a(8) = 4676049710123077 = (11^8)*13*1678009, reverse(a(8)) = 7703210179406764 = (11^8)*2*2*157*57223.
		

Crossrefs

Cf. A004086, A055483, A069554, A071686 (=2^n), A072005 (=3^n), A072021 (=5^n), A072050 (=7^n).

Formula

a(n) = A069554(11^n).

Extensions

a(9)-a(11) from Sean A. Irvine, Sep 02 2024
Showing 1-4 of 4 results.