cp's OEIS Frontend

A255642 a(n) = n*((n mod 3)*(n mod 5)-((n mod 3)+(n mod 5))).

%I A255642 #10 Mar 01 2015 16:50:34
%S A255642 0,-1,0,-9,-4,-10,-6,-7,8,-36,-10,-11,-24,-13,28,0,-16,0,-54,-19,-40,
%T A255642 -21,-22,23,-96,-25,-26,-54,-28,58,0,-31,0,-99,-34,-70,-36,-37,38,
%U A255642 -156,-40,-41,-84,-43,88,0,-46,0,-144,-49,-100,-51,-52,53,-216,-55,-56,-114,-58,118,0,-61,0,-189,-64,-130,-66,-67,68,-276,-70,-71,-144,-73,148,0
%N A255642 a(n) = n*((n mod 3)*(n mod 5)-((n mod 3)+(n mod 5))).
%C A255642 a(n) = 0 for n == {0,2} mod 15.
%H A255642 Colin Barker, <a href="/A255642/b255642.txt">Table of n, a(n) for n = 0..1000</a>
%F A255642 Empirical g.f. x*(2*x^20 -6*x^19 +6*x^17 -3*x^16 -14*x^15 +38*x^14 -46*x^13 +26*x^12 -16*x^11 -10*x^10 +48*x^9 -31*x^8 -4*x^7 -x^6 +8*x^5 -11*x^4 +14*x^3 -10*x^2 +2*x -1) / ((x -1)^2*(x^2 +x +1)^2*(x^8 -x^7 +x^5 -x^4 +x^3 -x +1)^2). - _Colin Barker_, Mar 01 2015
%t A255642 Table[x*(Mod[x,3]*Mod[x,5]-(Mod[x,3]+Mod[x,5])),{x,0,100}]
%o A255642 (PARI) vector(100, n, n*((n%3)*(n%5)-((n%3)+(n%5)))) \\ _Colin Barker_, Mar 01 2015
%K A255642 sign,easy
%O A255642 0,4
%A A255642 _Zak Seidov_, Mar 01 2015