A304335 - OEIS

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A304335

Sum of digits of (2*n-1)!!.

1

1, 1, 3, 6, 6, 18, 18, 18, 18, 36, 45, 45, 36, 63, 72, 72, 90, 90, 108, 108, 126, 108, 144, 144, 135, 144, 153, 180, 180, 171, 180, 198, 198, 189, 216, 243, 243, 234, 252, 225, 243, 261, 252, 297, 306, 333, 360, 324, 342, 342, 315, 360, 369, 378, 396, 387, 387, 414

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,3

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..1000

FORMULA

a(n) = A007953(A001147(n)).

MAPLE

a:= n-> add(i, i=convert(doublefactorial(2*n-1), base, 10)):

seq(a(n), n=0..60); # Alois P. Heinz, May 11 2018

PROG

(PARI) {a(n) = sumdigits((2*n)!/(n!*2^n))}

CROSSREFS

Cf. A001147, A004152.

Sequence in context: A103463 A370154 A265026 * A223048 A319446 A181372

Adjacent sequences: A304332 A304333 A304334 * A304336 A304337 A304338

KEYWORD

nonn,base

AUTHOR

Seiichi Manyama, May 11 2018

STATUS

approved