A380485 Numbers congruent to {0, 1, 2, 3, 4, 5} mod 30.

0, 1, 2, 3, 4, 5, 30, 31, 32, 33, 34, 35, 60, 61, 62, 63, 64, 65, 90, 91, 92, 93, 94, 95, 120, 121, 122, 123, 124, 125, 150, 151, 152, 153, 154, 155, 180, 181, 182, 183, 184, 185, 210, 211, 212, 213, 214, 215, 240, 241, 242, 243, 244, 245, 270, 271, 272, 273, 274, 275, 300, 301, 302, 303, 304, 305, 330, 331, 332, 333

Offset

1,3

Comments

Numbers k for which A276086(k) is not a multiple of 5.

Odd bisection gives numbers that are congruent to {0, 2, 4} mod 30, thus when halved, congruent to {0, 1, 2} mod 15, thus terms of A267711, numbers k such that k mod 3 = k mod 5.

Links

Table of n, a(n) for n=1..70.

Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,1,-1).

Formula

a(2*n-1) = 2*A267711(n).

From Elmo R. Oliveira, Jul 02 2026: (Start)

a(n) = a(n-1) + a(n-6) - a(n-7) for n > 7.

G.f.: x^2*(1 + x + x^2 + x^3 + x^4 + 25*x^5) / ((1-x)^2 * (1+x) * (1-x+x^2) * (1+x+x^2)). (End)

Mathematica

Select[Range[0, 333], Mod[#, 30] < 6 &] (* Amiram Eldar, Feb 03 2025 *)

Prog

(PARI) is_A380485(n) = !((n\6)%5);
(PARI) is_A380485(n) = ((n%30)<6);

Crossrefs

Cf. A276086, A380484 (characteristic function), A380486 (complement).

Cf. also A267711 (odd bisection halved).

Sequence in context: A250260 A345306 A086130 * A024636 A004845 A124128

Adjacent sequences: A380482 A380483 A380484 * A380486 A380487 A380488

Keyword

nonn,easy,changed

Author

Antti Karttunen, Feb 03 2025

Status

approved