cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A152146 Triangle read by rows: T(n,k) (n >= 0, 0 <= k <= n) = number of partitions of 2n into 2k odd parts.

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%I A152146 #24 Feb 28 2024 11:44:05
%S A152146 1,0,1,0,1,1,0,2,1,1,0,2,2,1,1,0,3,3,2,1,1,0,3,5,3,2,1,1,0,4,6,5,3,2,
%T A152146 1,1,0,4,9,7,5,3,2,1,1,0,5,11,11,7,5,3,2,1,1,0,5,15,14,11,7,5,3,2,1,1,
%U A152146 0,6,18,20,15,11,7,5,3,2,1,1,0,6,23,26,22,15,11,7,5,3,2,1,1
%N A152146 Triangle read by rows: T(n,k) (n >= 0, 0 <= k <= n) = number of partitions of 2n into 2k odd parts.
%C A152146 In both this and A152157, reading columns downwards "converges" to A000041.
%C A152146 Also the number of strict integer partitions of 2n with alternating sum 2k. Also the number of normal integer partitions of 2n of which 2k parts are odd, where a partition is normal if it covers an initial interval of positive integers. - _Gus Wiseman_, Jun 20 2021
%H A152146 Alois P. Heinz, <a href="/A152146/b152146.txt">Rows n = 0..200, flattened</a>
%F A152146 T(n,k) = A152140(2n,2k).
%e A152146 Triangle begins:
%e A152146   1
%e A152146   0  1
%e A152146   0  1  1
%e A152146   0  2  1   1
%e A152146   0  2  2   1   1
%e A152146   0  3  3   2   1   1
%e A152146   0  3  5   3   2   1   1
%e A152146   0  4  6   5   3   2   1  1
%e A152146   0  4  9   7   5   3   2  1  1
%e A152146   0  5 11  11   7   5   3  2  1  1
%e A152146   0  5 15  14  11   7   5  3  2  1  1
%e A152146   0  6 18  20  15  11   7  5  3  2  1  1
%e A152146   0  6 23  26  22  15  11  7  5  3  2  1  1
%e A152146   0  7 27  35  29  22  15 11  7  5  3  2  1  1
%e A152146   0  7 34  44  40  30  22 15 11  7  5  3  2  1 1
%e A152146   0  8 39  58  52  42  30 22 15 11  7  5  3  2 1 1
%e A152146   0  8 47  71  70  55  42 30 22 15 11  7  5  3 2 1 1
%e A152146   0  9 54  90  89  75  56 42 30 22 15 11  7  5 3 2 1 1
%e A152146   0  9 64 110 116  97  77 56 42 30 22 15 11  7 5 3 2 1 1
%e A152146   0 10 72 136 146 128 100 77 56 42 30 22 15 11 7 5 3 2 1 1
%e A152146 From _Gus Wiseman_, Jun 20 2021: (Start)
%e A152146 For example, row n = 6 counts the following partitions (B = 11):
%e A152146   (75)  (3333)  (333111)  (33111111)  (3111111111)  (111111111111)
%e A152146   (93)  (5331)  (531111)  (51111111)
%e A152146   (B1)  (5511)  (711111)
%e A152146         (7311)
%e A152146         (9111)
%e A152146 The corresponding strict partitions are:
%e A152146   (7,5)      (8,4)      (9,3)    (10,2)   (11,1)  (12)
%e A152146   (6,5,1)    (5,4,3)    (7,3,2)  (9,2,1)
%e A152146   (5,4,2,1)  (6,4,2)    (8,3,1)
%e A152146              (7,4,1)
%e A152146              (6,3,2,1)
%e A152146 The corresponding normal partitions are:
%e A152146   43221    33321     3321111    321111111   21111111111  111111111111
%e A152146   322221   332211    32211111   2211111111
%e A152146   2222211  432111    222111111
%e A152146            3222111
%e A152146            22221111
%e A152146 (End)
%p A152146 b:= proc(n, i) option remember; `if`(n=0, 1, `if`(i<1, 0,
%p A152146       b(n, i-2)+`if`(i>n, 0, expand(sqrt(x)*b(n-i, i)))))
%p A152146     end:
%p A152146 T:= n-> (p-> seq(coeff(p, x, i), i=0..n))(b(2*n, 2*n-1)):
%p A152146 seq(T(n), n=0..12);  # _Alois P. Heinz_, Jun 21 2021
%t A152146 ats[y_]:=Sum[(-1)^(i-1)*y[[i]],{i,Length[y]}];
%t A152146 Table[Length[Select[IntegerPartitions[n],UnsameQ@@#&&ats[#]==k&]],{n,0,30,2},{k,0,n,2}] (* _Gus Wiseman_, Jun 20 2021 *)
%Y A152146 Cf. A035294 (row sums), A107379, A152140, A152157.
%Y A152146 Column k = 1 is A004526.
%Y A152146 Column k = 2-8 is A026810 - A026816.
%Y A152146 The non-strict version is A239830.
%Y A152146 The reverse non-strict version is A344610.
%Y A152146 The reverse version is A344649
%Y A152146 A000041 counts partitions of 2n with alternating sum 0, ranked by A000290.
%Y A152146 A067659 counts strict partitions of odd length.
%Y A152146 A103919 counts partitions by sum and alternating sum (reverse: A344612).
%Y A152146 A124754 gives alternating sum of standard compositions (reverse: A344618).
%Y A152146 A316524 is the alternating sum of the prime indices of n (reverse: A344616).
%Y A152146 A344611 counts partitions of 2n with reverse-alternating sum >= 0.
%Y A152146 Cf. A006330, A027187, A116406, A120452, A239829, A343941, A344607, A344608, A344609, A344650, A344651, A344739, A344741.
%K A152146 nonn,tabl
%O A152146 0,8
%A A152146 _R. J. Mathar_, Sep 25 2009, indices corrected Jul 09 2012