A074179 a(1) = 1, a(n) = smallest multiple of n divisible by the sum of all previous terms.

1, 2, 3, 12, 90, 108, 1512, 1728, 3456, 34560, 456192, 497664, 12939264, 13934592, 139345920, 167215104, 5685313536, 6019743744, 228750262272, 240789749760, 481579499520, 10594748989440, 265831883735040, 277389791723520

Offset: 1

Author

Amarnath Murthy, Aug 31 2002

Keywords

• nonn

Comments

First differences of A135504. - David Radcliffe, Jun 23 2025

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..973

Crossrefs

Cf. A057827, A135504.

Programs

Maple

a[1] := 1:a[2] := 2:s := 3:for n from 3 to 50 do a[n] := lcm(s,n):s := s+a[n]:od:seq(a[k],k=1..50);

Mathematica

nxt[{n_,a_,t_}]:={n+1,LCM[n+1,t],t+LCM[n+1,t]}; NestList[nxt,{1,1,1},30][[All,2]] (* Harvey P. Dale, Dec 06 2018 *)

PARI

lista(nn) = my(va=vector(nn)); va[1]=1; for (n=2, nn, va[n] = lcm(n, vecsum(va))); va; \\ Michel Marcus, Nov 11 2020

Formula

a(n) = lcm(n, Sum_{k=1..n-1} a(k)), with a(1) = 1. - Michel Marcus, Nov 11 2020

Extensions

Corrected and extended by Sascha Kurz, Feb 12 2003