login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A344145 Positive numbers m such that A020330^k(m) belongs to A344022 for any k >= 0 (where f^k denotes the k-th iterate of f). 2
2, 9, 10, 12, 35, 37, 38, 41, 42, 44, 49, 50, 52, 56, 139, 141, 142, 147, 149, 150, 153, 154, 156, 163, 165, 166, 169, 170, 172, 177, 178, 180, 184, 197, 198, 201, 202, 204, 209, 210, 212, 216, 226, 228, 232, 555, 557, 558, 563, 565, 566, 569, 570, 587, 589 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The binary expansion of a term, say (b_1, ..., b_m), encodes an m-periodic nonintersecting infinite walk made of unit steps, with a +90-degree turn (resp. a -90-degree turn) at positions X=k' such that b_k = 1 (resp. b_k = 0) with k = k' mod m.

All positive terms of A002450 belong to this sequence.

LINKS

Table of n, a(n) for n=1..55.

Rémy Sigrist, Illustration of initial terms

EXAMPLE

See illustration in Links section.

PROG

(PARI) is(n) = { my (b=if (n, binary(n), [0]), d=1, s=[d], z=2*d); b=concat([b, b, b, b]); for (k=1, #b, if (b[k], d*=I, d/=I); if (setsearch(s, z+=d), return (0), s=setunion(s, [z]); z+=d)); return (1) }

CROSSREFS

Cf. A002450, A020330, A344022.

Sequence in context: A226841 A218560 A031443 * A051017 A078180 A058890

Adjacent sequences:  A344142 A344143 A344144 * A344146 A344147 A344148

KEYWORD

nonn,base

AUTHOR

Rémy Sigrist, May 10 2021

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 26 13:17 EDT 2022. Contains 354092 sequences. (Running on oeis4.)