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A282693 Numbers n such that n = (sum of digits of n)*((sum of digits of n) + 1). 0
0, 12, 42, 90, 156 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..5.

EXAMPLE

0=0*(0+1). 12=(1+2)*(1+2+1). 42=(4+2)*(4+2+1). 90=(9+0)*(9+0+1). 156=(1+5+6)*(1+5+6+1)

MATHEMATICA

fQ[n_] := Block[{a = Plus @@ IntegerDigits@ n}, a*(a +1) == n]; Select[ Range[0, 1000], fQ] (* Robert G. Wilson v, Feb 24 2017 *)

PROG

(VBA)

Sub calcul()

Sheets("Result").Select

Range("A1").Select

For i = 1 To 10000000

Sum = 0

For k = 1 To Len(i)

Sum = Sum + Mid(i, k, 1)

Next

res = Sum * (Sum + 1)

If res = i Then

ActiveCell.Value = i

ActiveCell.Offset(1, 0).Select

End If

Next

End Sub

CROSSREFS

Sequence in context: A241854 A085798 A270700 * A045945 A210206 A005901

Adjacent sequences:  A282690 A282691 A282692 * A282694 A282695 A282696

KEYWORD

bref,base,fini,full,nonn

AUTHOR

Shmelev Aleksei, Feb 24 2017

STATUS

approved

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Last modified January 17 16:47 EST 2018. Contains 297822 sequences.