A070290 - OEIS

A070290

a(n) = lcm(8,n)/gcd(8,n).

8, 4, 24, 2, 40, 12, 56, 1, 72, 20, 88, 6, 104, 28, 120, 2, 136, 36, 152, 10, 168, 44, 184, 3, 200, 52, 216, 14, 232, 60, 248, 4, 264, 68, 280, 18, 296, 76, 312, 5, 328, 84, 344, 22, 360, 92, 376, 6, 392, 100, 408, 26, 424, 108, 440, 7, 456, 116, 472, 30, 488

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OFFSET

1,1

COMMENTS

Only 63 of the first 1000 terms are odd and each occurs at index 8+16k. - Harvey P. Dale, Mar 03 2026

LINKS

Table of n, a(n) for n=1..61.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,-1).

FORMULA

From R. J. Mathar, Feb 12 2019: (Start)

a(n) = A109049(n) / A109011(n).

a(n) = 2*a(n-8) - a(n-16). (End)

Sum_{k=1..n} a(k) ~ (293/128)*n^2. - Amiram Eldar, Oct 07 2023

G.f.: x*(8 + 4*x + 24*x^2 + 2*x^3 + 40*x^4 + 12*x^5 + 56*x^6 + x^7 + 56*x^8 + 12*x^9 + 40*x^10 + 2*x^11 + 24*x^12 + 4*x^13 + 8*x^14) / (1 - x^8)^2. - Elmo R. Oliveira, May 16 2026

MATHEMATICA

LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, -1}, {8, 4, 24, 2, 40, 12, 56, 1, 72, 20, 88, 6, 104, 28, 120, 2}, 70] (* Georg Fischer, Feb 27 2019 *)

(* Alternative: *)

Array[LCM[8, #]/GCD[8, #]&, 70] (* Harvey P. Dale, Mar 03 2026 *)

CROSSREFS

Cf. A070291, A070292, A070293, A109011, A109049.

Sequence in context: A248293 A151726 A380559 * A307266 A173855 A143368

Adjacent sequences: A070287 A070288 A070289 * A070291 A070292 A070293

KEYWORD

easy,nonn,changed

AUTHOR

Amarnath Murthy, May 10 2002

STATUS

approved