A117512 Triangular numbers for which the sum of the digits is a prime number.

3, 21, 120, 210, 300, 496, 595, 946, 1378, 1891, 2278, 2485, 2926, 3655, 3916, 4186, 4465, 4753, 5356, 5671, 6328, 6670, 7381, 7750, 8128, 8515, 8911, 9316, 9730, 10011, 10585, 11476, 11935, 12880, 13366, 13861, 14365, 15931, 16471, 18145, 18721

Offset

1,1

Links

Table of n, a(n) for n=1..41.

Example

595 is in the sequence because (1) it is a triangular number and (2) the sum of its digits 5+9+5=19 is a prime number.

Mathematica

With[{trnos=Accumulate[Range[200]]}, Select[trnos, PrimeQ[Total[IntegerDigits[#]]]&]]  (* Harvey P. Dale, Feb 14 2011 *)

Crossrefs

Cf. A000217.

Sequence in context: A084159 A046727 A283421 * A068127 A247247 A322185

Adjacent sequences: A117509 A117510 A117511 * A117513 A117514 A117515

Keyword

nonn,base

Author

Luc Stevens (lms022(AT)yahoo.com), Apr 26 2006

Status

approved