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 A117082 Octagonal numbers for which the sum of the digits is also a octagonal number. 1
 0, 1, 8, 341, 1160, 4485, 6816, 9633, 12936, 16725, 20501, 25761, 30401, 36741, 42960, 64533, 81345, 90480, 131880, 143445, 168033, 181056, 208560, 238008, 253461, 269400, 302736, 338016, 375240, 414408, 434721, 455520, 520833, 590520 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Harvey P. Dale, Table of n, a(n) for n = 0..1000 EXAMPLE 1160 is in the sequence because (1) it is a octagonal number and (2)the sum of its digits 1+1+6+0=8 is also a octagonal number. MATHEMATICA octQ[n_] := IntegerQ[(Sqrt[3 n + 1] + 1)/3]; t = {0}; Do[x = n*(3 n - 2); If[octQ[Plus @@ IntegerDigits[x]], AppendTo[t, x]], {n, 450}]; t (* Jayanta Basu, Jul 13 2013 *) With[{oct=PolygonalNumber[8, Range[0, 500]]}, Select[oct, MemberQ[oct, Total[ IntegerDigits[ #]]]&]] (* The program uses the PolygonalNumber function from Mathematica version 10 *) (* Harvey P. Dale, Mar 06 2016 *) CROSSREFS Cf. A000567. Sequence in context: A258745 A071306 A214511 * A061458 A135067 A002781 Adjacent sequences:  A117079 A117080 A117081 * A117083 A117084 A117085 KEYWORD base,nonn AUTHOR Luc Stevens (lms022(AT)yahoo.com), Apr 17 2006 STATUS approved

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Last modified April 16 17:01 EDT 2021. Contains 343050 sequences. (Running on oeis4.)