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

Offset: 0

Author

Mitch Harris, Jun 18 2005

Keywords

• nonn
• easy

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.

Crossrefs

Cf. A106611, A109013, A109042.

Programs

Magma

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

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 *)

PARI

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

Sage

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

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