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A282693
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Numbers k such that k = (sum of digits of k)*((sum of digits of k) + 1).
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0
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OFFSET
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1,2
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LINKS
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EXAMPLE
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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).
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MATHEMATICA
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fQ[n_] := Block[{a = Plus @@ IntegerDigits@ n}, a*(a +1) == n]; Select[ Range[0, 1000], fQ] (* Robert G. Wilson v, Feb 24 2017 *)
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PROG
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(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
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CROSSREFS
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KEYWORD
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bref,base,fini,full,nonn
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AUTHOR
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STATUS
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approved
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