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A117312
Triangular numbers for which the sum of the digits is a heptagonal number.
1
0, 1, 10, 378, 666, 990, 1485, 1953, 2556, 2628, 4095, 4851, 4950, 6903, 9045, 9180, 10296, 11628, 11781, 14535, 14706, 16290, 19503, 19701, 21528, 23436, 25425, 27261, 29403, 31626, 33930, 34191, 36315, 39060, 41328, 41616, 44253, 52326
OFFSET
0,3
LINKS
EXAMPLE
378 is in the sequence because (1) it is a triangular number and (2) the sum of its digits 3+7+8=18 is a heptagonal number.
MATHEMATICA
Join[{0}, Select[Accumulate[Range[0, 500]], IntegerQ[(3+Sqrt[40*Total[ IntegerDigits[ #]]+9])/10]&]] (* Harvey P. Dale, Aug 10 2013 *)
CROSSREFS
Sequence in context: A301311 A291530 A358801 * A200804 A277663 A000591
KEYWORD
base,nonn
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), Apr 26 2006
STATUS
approved