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A255642 a(n) = n*((n mod 3)*(n mod 5)-((n mod 3)+(n mod 5))). 2

%I

%S 0,-1,0,-9,-4,-10,-6,-7,8,-36,-10,-11,-24,-13,28,0,-16,0,-54,-19,-40,

%T -21,-22,23,-96,-25,-26,-54,-28,58,0,-31,0,-99,-34,-70,-36,-37,38,

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

%C a(n) = 0 for n == {0,2} mod 15.

%H Colin Barker, <a href="/A255642/b255642.txt">Table of n, a(n) for n = 0..1000</a>

%F 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 Table[x*(Mod[x,3]*Mod[x,5]-(Mod[x,3]+Mod[x,5])),{x,0,100}]

%o (PARI) vector(100, n, n*((n%3)*(n%5)-((n%3)+(n%5)))) \\ _Colin Barker_, Mar 01 2015

%K sign,easy

%O 0,4

%A _Zak Seidov_, Mar 01 2015

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Last modified September 17 13:00 EDT 2019. Contains 327131 sequences. (Running on oeis4.)