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A152826
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Numbers with the following property that they are divisible by the product of the digit-sums of their neighbours.
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105, 672, 1200, 1530, 1560, 2145, 2907, 3060, 3432, 4704, 5814, 6006, 6120, 6240, 8721, 9570, 10710, 10752, 10920, 11154, 11628, 11700, 12240, 12441, 13260, 14535, 15015, 16302, 17442, 19656, 20163, 20280, 20832, 21420, 22620, 23256, 23400
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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REFERENCES
| Die WURZEL - Zeitschrift fuer Mathematik, 42. Jahrgang, Dezember 2008, Seite 287, WURZEL-Aufgabe sigma55 von Reiner Moewald, Germersheim.
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MATHEMATICA
| Select[Range[50000], Divisible[#, Total[IntegerDigits[#-1]]Total[IntegerDigits[#+1]]]&]
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PROG
| (Other) class Program { static void Main(string[] args) { for (int i = 1; i < 1000000; i++) { int q1 = quersumme(i - 1); int q2 = quersumme(i + 1); if ((double)i % ((double)q1 * (double)q2) == 0) { Console.WriteLine(i); } } Console.ReadLine(); } static int quersumme(int num) { string n = num.ToString(); int retval = 0; int i = n.Length - 1; while (i >= 0) { retval += Int32.Parse(n.Substring(i, 1)); i--; } return retval; } }
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CROSSREFS
| Sequence in context: A200834 A143041 A078420 * A133767 A166816 A166798
Adjacent sequences: A152823 A152824 A152825 * A152827 A152828 A152829
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KEYWORD
| nonn,base
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AUTHOR
| Gerhard Palme (GerhardPalme(AT)gmx.de), Dec 13 2008
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EXTENSIONS
| Mathematica program provided by Harvey P. Dale, Dec. 11, 2010
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