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 A282693 Numbers k such that k = (sum of digits of k)*((sum of digits of k) + 1). 0
 0, 12, 42, 90, 156 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS 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: A085798 A335150 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 26 20:49 EST 2022. Contains 350599 sequences. (Running on oeis4.)