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 A318701 Tetrahedral numbers that are not divisible by any smaller tetrahedral number except 1. 2
 1, 4, 10, 35, 165, 286, 969, 1771, 2925, 3654, 4495, 9139, 12341, 16215, 23426, 32509, 39711, 47905, 52394, 67525, 79079, 91881, 105995, 129766, 138415, 156849, 176851, 209934, 221815, 246905, 273819, 302621, 366145, 383306, 437989, 477191, 540274, 562475, 657359, 708561, 762355, 848046, 939929, 1004731 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 EXAMPLE 4 is a term because it is divisible by 1. 10 is a term because it is divisible by 1 but not by 4. MAPLE count:= 1: Res:= NULL: for i from 2 while count < 100 do   r:= i*(i+1)*(i+2)/6;   if not ormap(t -> (r/t)::integer, [Res]) then     Res:= Res, r;     count:= count+1;   fi od: 1, Res; # Robert Israel, Dec 28 2018 MATHEMATICA t[n_]:=n(n+1)(n+2)/6; tQ[n_] := Module[{ans=True, tn=t[n]}, Do[If[Divisible[tn, t[i]], ans=False; Break[]], {i, 2, n-1}]; ans]; t[Select[Range[100], tQ]] (* Amiram Eldar, Nov 14 2018 *) PROG (PARI) t(n) = n*(n+1)*(n+2)/6; isok(n) = my(tn=t(n)); for(i=2, n-1, if (!(tn % t(i)), return (0))); return (1); lista(nn) = for (n=1, nn, if (isok(n), print1(t(n), ", "))); \\ Michel Marcus, Sep 29 2018 CROSSREFS Cf. A000292, A319788. Sequence in context: A059710 A149177 A149178 * A152916 A222506 A108596 Adjacent sequences:  A318698 A318699 A318700 * A318702 A318703 A318704 KEYWORD nonn AUTHOR Torlach Rush, Aug 31 2018 EXTENSIONS a(1) = 1 inserted by Michel Marcus, Nov 09 2018 STATUS approved

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Last modified May 10 22:16 EDT 2021. Contains 343780 sequences. (Running on oeis4.)