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A131771 First differences (A131772) equal this sequence with zeros inserted at positions {m*(m+1)/2, m>=0}. 4

%I #2 Mar 30 2012 18:37:04

%S 1,1,2,4,4,8,12,20,20,32,52,72,104,104,156,228,332,436,592,592,820,

%T 1152,1588,2180,2772,3592,3592,4744,6332,8512,11284,14876,18468,23212,

%U 23212,29544,38056,49340,64216,82684,105896,129108,158652,158652,196708

%N First differences (A131772) equal this sequence with zeros inserted at positions {m*(m+1)/2, m>=0}.

%C Partial sums yield distinct terms of this sequence.

%e Partial sums (A131770) begin:

%e [1,2,4,8,12,20,32,52,72,104,156,228,332,436,592,...].

%e First differences (A131772) begin:

%e [1,0,1,2,0,4,4,8,0,12,20,20,32,0,52,72,104,104,156,0,228,332,436,592,592,...].

%o (PARI) {A131770(n)=if(n<0,0,if(n==0,1,A131770(n-1)+A131770(n-(sqrtint(8*n+17)-3)\2)))} {a(n)=A131770(n)-A131770(n-1)}

%Y Cf. A131770 (partial sums), A131772 (first differences).

%K nonn

%O 0,3

%A _Paul D. Hanna_, Jul 14 2007

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Last modified March 29 04:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)