Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #37 Sep 08 2022 08:45:14
%S 1,3,4,7,6,12,8,15,13,18,12,28,14,24,24,31,18,39,20,42,32,36,24,60,31,
%T 42,40,56,30,72,32,63,48,54,48,91,38,60,56,90,42,96,44,84,78,72,48,
%U 124,57,93,72,98,54,120,72,120,80,90,60,168,62,96,104,127,84,144,68,126,96
%N a(n) = sigma(n) mod 210.
%C Agrees with A000203(n) for n <= 89; sigma(90) = 234. - _Omar E. Pol_, Feb 02 2013
%C This sequence is not multiplicative. For example, at a(84) = 14 which is not a(3)*a(4)*a(7) = 224. - _Andrew Howroyd_, Aug 23 2018
%H Michael De Vlieger, <a href="/A097012/b097012.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A000203(n) mod 210.
%t Array[Mod[DivisorSigma[1, #], 210] &, 69] (* _Michael De Vlieger_, Jul 24 2017 *)
%o (PARI) a(n) = sigma(n) % 210; \\ _Michel Marcus_, Dec 19 2013
%o (Magma) [SumOfDivisors(n) mod 210: n in [1..70]]; // _Vincenzo Librandi_, Jul 25 2017
%Y Cf. A000203, A084301, A084303, A097011, A097013, A097014, A097015.
%K nonn
%O 1,2
%A _Labos Elemer_, Aug 19 2004