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A108220 Numbers n such that concatenating n and the sum of factorials of the digits of n produces a square. 0
3, 102, 122, 202, 1102, 15031, 244134, 244233, 434412, 495918, 1267396, 1300035, 1324340, 1635150, 3442657, 3878374, 5064314, 6175125, 6181308, 10320734, 10560355, 10586434, 10730603, 10804230, 11544642, 16224135, 17523855 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..27.

EXAMPLE

495918 is in the sequence because 4!+9!+5!+9!+1!+8! = 766225 and

495918766225 = 704215^2.

MATHEMATICA

sfdsQ[n_]:=Module[{f=Total[IntegerDigits[n]!]}, IntegerQ[ Sqrt[ n*10^IntegerLength[ f]+ f]]]; Select[Range[176*10^5], sfdsQ] (* Harvey P. Dale, Jul 06 2020 *)

CROSSREFS

Cf. A061602, A109016.

Sequence in context: A069457 A142416 A110625 * A130733 A037062 A290027

Adjacent sequences:  A108217 A108218 A108219 * A108221 A108222 A108223

KEYWORD

base,nonn

AUTHOR

Jason Earls, Jun 16 2005

EXTENSIONS

Extended by Don Reble, Nov 21 2006

STATUS

approved

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Last modified November 29 06:00 EST 2021. Contains 349416 sequences. (Running on oeis4.)