A343752 - OEIS

%I #19 Jun 13 2021 06:05:15

%S 1,3,3,7,12,6,13,21,30,10,21,33,46,60,15,31,48,66,85,105,21,43,66,90,

%T 115,141,168,28,57,87,118,150,183,217,252,36,73,111,150,190,231,273,

%U 316,360,45,91,138,186,235,285,336,388,441,495,55,111,168,226

%N a(1) = 1; for n > 1, a(n) = n if a(n-1) is divisible by n, otherwise a(n) = a(n-1)+n.

%H Rémy Sigrist, <a href="/A343752/b343752.txt">Table of n, a(n) for n = 1..10010</a>

%F Apparently, a(n) = n iff n belongs to A000217. - _Rémy Sigrist_, May 16 2021

%t RecurrenceTable[{a[n + 1] == If[Divisible[a[n], n + 1], n + 1, a[n] + n + 1], a[1] == 1}, a, {n, 1, 100}]

%o (PARI) lista(nn) = {my(va = vector(nn)); va[1] = 1; for (n=2, nn, va[n] = va[n-1]; if (va[n-1] % n, va[n] += n, va[n]);); va;} \\ _Michel Marcus_, May 17 2021

%Y Cf. A000217.

%K nonn

%O 1,2

%A _Harvey L. Devereux_, Apr 27 2021