A109051 - OEIS

A109051

a(n) = lcm(n,10).

0, 10, 10, 30, 20, 10, 30, 70, 40, 90, 10, 110, 60, 130, 70, 30, 80, 170, 90, 190, 20, 210, 110, 230, 120, 50, 130, 270, 140, 290, 30, 310, 160, 330, 170, 70, 180, 370, 190, 390, 40, 410, 210, 430, 220, 90, 230, 470, 240, 490, 50, 510, 260, 530, 270, 110, 280

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OFFSET

0,2

LINKS

Amiram Eldar, Table of n, a(n) for n = 0..10000

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

Index entries for sequences related to lcm's.

FORMULA

a(n) = n*10/gcd(n, 10).

a(n) = 10*n/A109013(n) = 10*A106611(n). - R. J. Mathar, Apr 18 2011

G.f.: 10*x*(1 +x +3*x^2 +2*x^3 +x^4 +3*x^5 +7*x^6 +4*x^7 +9*x^8 +x^9 +9*x^10 +4*x^11 +7*x^12 +3*x^13 +x^14 +2*x^15 +3*x^16 +x^17 +x^18)/(1 -x^10)^2. - Robert Israel, Feb 23 2016

Sum_{k=1..n} a(k) ~ (63/20) * n^2. - Amiram Eldar, Nov 26 2022

MAPLE

q:= [seq(10/igcd(i, 10), i=1..10)]:

[0, seq(seq((10*i+j)*q[j], j=1..10), i=0..10)]; # Robert Israel, Feb 23 2016

MATHEMATICA

a[n_] := LCM[n, 10]; Array[a, 60, 0] (* Amiram Eldar, Nov 26 2022 *)

PROG

(Sage) [lcm(n, 10)for n in range(0, 57)] # Zerinvary Lajos, Jun 07 2009

(Magma) [Lcm(n, 10): n in [0..100]]; // Vincenzo Librandi, Apr 18 2011

(PARI) a(n) = lcm(n, 10); \\ Michel Marcus, Feb 23 2016

CROSSREFS

Cf. A106611, A109013, A109042.