A250036 Numbers n such that m = floor(n/4) is coprime to n and, if nonzero, m is also a term of the sequence.

1, 4, 5, 6, 7, 17, 19, 21, 22, 23, 25, 29, 30, 31, 69, 70, 71, 77, 78, 79, 85, 86, 89, 91, 93, 94, 95, 101, 102, 103, 117, 118, 119, 121, 125, 126, 127, 277, 278, 281, 283, 285, 286, 287, 309, 310, 311, 313, 317, 318, 319, 341, 342, 343, 345, 347, 357, 358

Offset: 1

Author

Stanislav Sykora, Dec 07 2014

Keywords

• nonn
• base

Comments

See the comments in A250040 which all apply, except for the setting of the base, b=4. In particular, they define the property RTC(b).

Links

• Stanislav Sykora, Table of n, a(n) for n = 1..10000
• Stanislav Sykora, PARI/GP scripts for genetic threads, with code and comments.
• Wikipedia, Coprime integers

Crossrefs

Cf. A250037, A250040.

Other lists of right-truncatable numbers with the property RTC(b): A250038 (b=16), A250040 (b=10), A250042 (b=9), A250044 (b=8), A250046 (b=7), A250048 (b=6), A250050 (b=5).

Programs

PARI

See the link.

PARI

is_rtc(n, b=4) =  {while (((m=gcd(n\b, n)) == 1), if (m == 0, return (1)); if ((n=n\b) == 0, return (1));); return (0);} \\ Michel Marcus, Jan 18 2015