A357704 - OEIS

A357704

Triangle read by rows where T(n,k) is the number of reversed integer partitions of n with half-alternating sum k, where k ranges from -n to n in steps of 2.

1, 0, 1, 0, 0, 2, 0, 0, 1, 2, 0, 0, 2, 0, 3, 0, 0, 2, 2, 0, 3, 0, 0, 3, 1, 3, 0, 4, 0, 0, 3, 2, 4, 2, 0, 4, 0, 0, 4, 2, 6, 2, 3, 0, 5, 0, 0, 4, 3, 5, 7, 3, 3, 0, 5, 0, 0, 5, 3, 8, 4, 10, 2, 4, 0, 6, 0, 0, 5, 4, 8, 6, 11, 9, 3, 4, 0, 6, 0, 0, 6, 4, 11, 5, 15, 8, 13, 3, 5, 0, 7

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OFFSET

0,6

COMMENTS

We define the half-alternating sum of a sequence (A, B, C, D, E, F, G, ...) to be A + B - C - D + E + F - G - ...

LINKS

Table of n, a(n) for n=0..90.

EXAMPLE

Triangle begins:

0 1

0 0 2

0 0 1 2

0 0 2 0 3

0 0 2 2 0 3

0 0 3 1 3 0 4

0 0 3 2 4 2 0 4

0 0 4 2 6 2 3 0 5

0 0 4 3 5 7 3 3 0 5

0 0 5 3 8 4 10 2 4 0 6

0 0 5 4 8 6 11 9 3 4 0 6

0 0 6 4 11 5 15 8 13 3 5 0 7

0 0 6 5 11 8 13 19 10 13 4 5 0 7

0 0 7 5 14 8 19 13 25 9 17 4 6 0 8

0 0 7 6 14 11 19 17 29 23 13 18 5 6 0 8

Row n = 7 counts the following reversed partitions:

. . (115) (124) (133) (11113) . (7)

(1114) (1222) (223) (111112) (16)

(1123) (11122) (25)

(1111111) (34)

MATHEMATICA

halfats[f_]:=Sum[f[[i]]*(-1)^(1+Ceiling[i/2]), {i, Length[f]}];

Table[Length[Select[Reverse/@IntegerPartitions[n], halfats[#]==k&]], {n, 0, 15}, {k, -n, n, 2}]

CROSSREFS

Row sums are A000041.

Last entry of row n is A008619(n).

The central column in the non-reverse case is A035363, skew A035544.

For original reverse-alternating sum we have A344612.

For original alternating sum we have A344651, ordered A097805.

The non-reverse version is A357637, skew A357638.

The central column is A357639, skew A357640.

The non-reverse ordered version (compositions) is A357645, skew A357646.

The skew-alternating version is A357705.

A351005 = alternately equal and unequal partitions, compositions A357643.

A351006 = alternately unequal and equal partitions, compositions A357644.

A357621 gives half-alternating sum of standard compositions, skew A357623.

A357629 gives half-alternating sum of prime indices, skew A357630.

A357633 gives half-alternating sum of Heinz partition, skew A357634.

Cf. A029862, A053251, A357136, A357189, A357487, A357488, A357631, A357632, A357641.

Sequence in context: A093085 A339059 A023555 * A294203 A143380 A143377

Adjacent sequences: A357701 A357702 A357703 * A357705 A357706 A357707

KEYWORD

nonn,tabl

AUTHOR

Gus Wiseman, Oct 10 2022

STATUS

approved