Search: id:A122061
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%I A122061
%S A122061 1,6,18,40,35,66,112,176,117,190,286,408,247,378,540,736,425,630,874,
%T A122061 1160,651,946,1288,1680,925,1326,1782,2296,1247,1770,2356,3008,1617,
%U A122061 2278,3010,3816,2035,2850,3744,4720,2501,3486,4558,5720,3015,4186,5452
%N A122061 First pentagonal number, 2nd hexagonal number, 3rd heptagonal number, 
               4th octagonal number and then repeat the same pattern: 5th pentagonal, 
               6th hexagonal, 7th heptagonal, 8th octagonal, etc.
%C A122061 From a quiz.
%D A122061 A. Wareham, Test Your Brain Power, Ward Lock Ltd (1995).
%F A122061 a(n) = n*(3*n-1)/2 if n=1 mod 4 or n*(4*n-2)/2 if n=2 mod 4 or n*(5*n-3)/
               2 if n=3 mod 4 or n*(6*n-4)/2 if n=0 mod 4
%o A122061 (PARI) for(n=1,60,m=(n+3)%4;print1(n*((m+3)*n-m-1)/2,","))
%Y A122061 Cf. A060354.
%Y A122061 Sequence in context: A005899 A129863 A035489 this_sequence A002411 A023658 
               A059834
%Y A122061 Adjacent sequences: A122058 A122059 A122060 this_sequence A122062 A122063 
               A122064
%K A122061 nonn
%O A122061 1,2
%A A122061 Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 14 2006

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