A031999 -id:A031999 - cp's OEIS frontend

A023760 Nialpdromes: digits in base 4 are in nonincreasing order.

0, 1, 2, 3, 4, 5, 8, 9, 10, 12, 13, 14, 15, 16, 20, 21, 32, 36, 37, 40, 41, 42, 48, 52, 53, 56, 57, 58, 60, 61, 62, 63, 64, 80, 84, 85, 128, 144, 148, 149, 160, 164, 165, 168, 169, 170, 192, 208, 212, 213, 224, 228, 229, 232, 233, 234, 240, 244, 245, 248

Offset: 1

Olivier Gérard

Vincenzo Librandi, Table of n, a(n) for n = 1..1001 (adapted to the new offset from _Bruno Berselli_)

Cf. A023786 (subset), A031999 (slightly different version).

Select[Range[0, 4000], Max[Differences[IntegerDigits[#, 4]]] <= 0 &] (* Vincenzo Librandi, Dec 26 2012 *)
Select[Range[0, 250], GreaterEqual@@IntegerDigits[#, 4] &] (* Ray Chandler, Jan 06 2014 *)

A023786 Katadromes: digits in base 4 are in strict descending order.

Original entry on oeis.org

0, 1, 2, 3, 4, 8, 9, 12, 13, 14, 36, 52, 56, 57, 228

Offset: 1

Olivier Gérard

No more terms are possible because, although infinitely many numbers have base 4 digits in descending order, like 256, none beyond 228 can have them in strictly descending order. - Alonso del Arte, Feb 08 2019

			228 in base 4 is 3210. Since those digits are in strictly descending order, 228 is in the sequence.
229 in base 4 is 3211. Although those digits are in descending order, the repeated digit 1 means 229 is not in the sequence.

Cf. A023760, A031999.

Select[Range[0, 255], Max[Differences[IntegerDigits[#, 4]]] < 0 &] (* Harvey P. Dale, Dec 15 2014 *)

cp's OEIS Frontend

A023760 Nialpdromes: digits in base 4 are in nonincreasing order.

Views

Author

Keywords

Links

Crossrefs

Programs

Mathematica