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A117674
Prime numbers whose sum of digits is a triangular number.
2
3, 19, 37, 73, 109, 127, 163, 181, 271, 307, 433, 523, 541, 613, 631, 811, 1009, 1063, 1117, 1153, 1171, 1423, 1531, 1621, 1801, 1999, 2017, 2053, 2143, 2161, 2251, 2341, 2503, 2521, 3061, 3313, 3331, 3511, 3889, 4051, 4231, 4789, 4969, 4987, 5023, 5113
OFFSET
1,1
LINKS
EXAMPLE
1999 is in the sequence because it is a prime number and the sum of its digits 1+9+9+9 = 28 is a triangular number.
MATHEMATICA
t={}; Do[m = Total[IntegerDigits[Prime[n]]]; If[IntegerQ[(Sqrt[8*m + 1]-1)/2], AppendTo[t, Prime[n]]], {n, 700}]; t (* Jayanta Basu, Apr 27 2013 *)
PROG
(PARI) isok(p) = isprime(p) && ispolygonal(sumdigits(p), 3); \\ Michel Marcus, Feb 08 2021
CROSSREFS
Intersection of A000040 and A187744.
Sequence in context: A187828 A088786 A147237 * A114704 A167053 A131542
KEYWORD
nonn,base
AUTHOR
Luc Stevens (lms022(AT)yahoo.com), Apr 27 2006
STATUS
approved