Search: id:A003679
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%I A003679 M3323
%S A003679 4,8,9,16,19,20,21,26,30,31,33,38,42,43,50,54,55,60,65,67,77,81,84,88,
%T A003679 89,90,96,99,100,101,111,112,113,120,125,131,135,138,142,154,159,160,
%U A003679 166,170,171,183,195,204,205,207,217,224,225,226,229,230,236,240,241
%N A003679 Numbers that are not the sum of 3 pentagonal numbers.
%C A003679 Guy's paper says that the sequence probably contains exactly 210 terms, 
               six of which require five pentagonal numbers: 9, 21, 31, 43, 55 and 
               89. The last term is conjectured to be 33066. - T. D. Noe (noe(AT)sspectra.com), 
               Apr 19 2006
%D A003679 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, 
               Academic Press, 1995 (includes this sequence).
%D A003679 R. K. Guy, Every number is expressible as the sum of how many polygonal 
               numbers?, Amer. Math. Monthly 101 (1994), 169-172.
%H A003679 T. D. Noe, <a href="b003679.txt">Table of n, a(n) for n = 1..210</a>
%H A003679 Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/
               PentagonalNumber.html">Pentagonal Number</a>
%t A003679 nn=200; pen=Table[n(3n-1)/2, {n,0,nn-1}]; lst=Range[pen[[ -1]]; Do[n=pen[[i]]+pen[[j]]+pen[[k]]; 
               If[n<=pen[[ -1]], lst=DeleteCases[lst,n]]], {i,nn}, {j,i,nn}, {k,
               j,nn}]; lst - T. D. Noe (noe(AT)sspectra.com), Apr 19 2006
%Y A003679 Cf. A117065 (primes in this sequence).
%Y A003679 Sequence in context: A166402 A034038 A069265 this_sequence A079432 A162215 
               A134344
%Y A003679 Adjacent sequences: A003676 A003677 A003678 this_sequence A003680 A003681 
               A003682
%K A003679 nonn,easy,nice
%O A003679 1,1
%A A003679 N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein

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