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A111300 Positive integers that are the difference between two double factorials. 2
0, 1, 2, 5, 6, 7, 12, 13, 14, 33, 40, 45, 46, 47, 57, 90, 97, 102, 103, 104, 279, 336, 369, 376, 381, 382, 383, 561, 840, 897, 930, 937, 942, 943, 944, 2895, 3456, 3735, 3792, 3825, 3832, 3837, 3838, 3839, 6555, 9450, 10011, 10290, 10347, 10380, 10387, 10392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

FORMULA

M!! - N!! where M and N positive integers.

EXAMPLE

7!! - 4!! = 7*5*3*1 - 4*2 = 105 - 8 = 97.

9!! - 5!! = 9*7*5*3*1 - 5*3*1 = 945 - 15 = 930.

MATHEMATICA

terms[n_]:=Sort[Union[Flatten[Table[j!!-i!!, {i, n}, {j, i, n}]]]]; terms[12] (* Enrique Pérez Herrero, May 21 2011 *)

CROSSREFS

Cf. A006882 (n!!).

Sequence in context: A282183 A103025 A134080 * A215761 A117548 A175135

Adjacent sequences:  A111297 A111298 A111299 * A111301 A111302 A111303

KEYWORD

easy,nonn

AUTHOR

Paolo P. Lava and Giorgio Balzarotti, Nov 02 2005

EXTENSIONS

Extended by T. D. Noe, May 22 2011

STATUS

approved

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Last modified August 20 13:04 EDT 2017. Contains 290835 sequences.