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 A337257 Number of even divisors of n!. 2
 0, 0, 1, 2, 6, 12, 24, 48, 84, 140, 240, 480, 720, 1440, 2376, 3696, 5040, 10080, 13824, 27648, 38880, 57600, 91200, 182400, 232320, 325248, 510048, 649152, 882000, 1764000, 2246400, 4492800, 5356800, 7618560, 11796480, 15925248 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..10000 FORMULA a(n) = A183063(n!). A336940(n) + a(n) = A027423(n) = A000005(n!). EXAMPLE The a(2) = 1 through a(5) = 12 divisors:   2  2  2   2      6  4   4         6   6         8   8         12  10         24  12             20             24             30             40             60             120 MATHEMATICA Table[Length[Select[Divisors[n!], EvenQ]], {n, 0, 15}] PROG (PARI) a(n) = sumdiv(n!, d, !(d%2)); \\ Michel Marcus, Aug 24 2020 CROSSREFS A336940 is the odd version. A000265 gives the maximum odd divisor of n. A001227 counts odd divisors. A183063 counts even divisors. Cf. A000005, A001013, A001055, A006939, A049606, A124010, A253249. Factorial numbers: A000142, A022559, A027423 (divisors), A048656, A071626, A076716 (factorizations), A325272, A325273, A325617, A336414, A336498. Sequence in context: A118224 A227068 A003680 * A051487 A111286 A058295 Adjacent sequences:  A337254 A337255 A337256 * A337258 A337259 A337260 KEYWORD nonn AUTHOR Gus Wiseman, Aug 23 2020 STATUS approved

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Last modified April 17 10:23 EDT 2021. Contains 343064 sequences. (Running on oeis4.)