A097654 - OEIS

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A097654

Numbers n such that n=|d_1!!-d_2!!+...+(-1)^(k-1)*d_k!!| where d_1 d_2 ... d_k is the decimal expansion of n.

2

1, 2, 3, 380

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

OFFSET

1,2

LINKS

Table of n, a(n) for n=1..4.

EXAMPLE

380 is in the sequence because 380=|3!!-8!!+0!!|.

MATHEMATICA

Do[h=IntegerDigits[n]; l=Length[h]; If[n==Abs[Sum[(-1)^(k-1) *h[[k]]!!, {k, l}]], Print[n]], {n, 4*9!!}]

CROSSREFS

Cf. A097653, A097655, A097643.

Sequence in context: A375236 A110931 A355323 * A156986 A066849 A071219

Adjacent sequences: A097651 A097652 A097653 * A097655 A097656 A097657

KEYWORD

base,fini,full,nonn

AUTHOR

Farideh Firoozbakht, Sep 10 2004

STATUS

approved