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A173345 Number of trailing zeros of the superfactorial of n (A000178). 1
0, 0, 0, 0, 1, 2, 3, 4, 5, 7, 9, 11, 13, 15, 18, 21, 24, 27, 30, 34, 38, 42, 46, 50, 56, 62, 68, 74, 80, 87, 94, 101, 108, 115, 123, 131, 139, 147, 155, 164, 173, 182, 191, 200, 210, 220, 230, 240, 250, 262, 274, 286, 298, 310, 323, 336, 349, 362, 375, 389, 403, 417 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..1000

MathWorld, Superfactorial

A. M. Oller-Marcen, J. Maria Grau, On the Base-b Expansion of the Number of Trailing Zeros of b^k!, J. Int. Seq. 14 (2011) 11.6.8

FORMULA

a(n) = Sum_{k=1..n} A027868(k). - Charles R Greathouse IV, Jun 10 2011

MATHEMATICA

a[n_] := Sum[Z10[i], {i, n}]; Z10[n_]:= Floor[Sum[Floor[n/5^i], {i, 1, Floor[Log[5, n]]}]]; Table[a[n], {n, 1, 200}]

PROG

(PARI) a(n)=my(t=0); sum(k=5, n, t+=valuation(k, 5)) \\ Charles R Greathouse IV, Jun 10 2011

CROSSREFS

Cf. A000178.

Sequence in context: A008732 A130520 A005706 * A226091 A064175 A000028

Adjacent sequences:  A173342 A173343 A173344 * A173346 A173347 A173348

KEYWORD

easy,base,nonn

AUTHOR

José María Grau Ribas, Feb 16 2010

STATUS

approved

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Last modified December 9 21:09 EST 2018. Contains 318023 sequences. (Running on oeis4.)