A118488 Squares for which the sum of the digits is a triangular number.

0, 1, 64, 100, 361, 1225, 2116, 3025, 5041, 6400, 10000, 17956, 18496, 21025, 23104, 26569, 29584, 32041, 36100, 38809, 47089, 54289, 58564, 59536, 63001, 68644, 69696, 77284, 82369, 87616, 88804, 94249, 110224, 117649, 122500, 128881, 130321

Offset

1,3

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

26569 = 163^2 is in the sequence because it is a square and the sum of its digits, 2+6+5+6+9 = 28, is a triangular number.

Mathematica

Select[Range[0, 361]^2, IntegerQ @ Sqrt[8 * Plus @@ IntegerDigits[#] + 1] &] (* Amiram Eldar, Mar 24 2021 *)

Prog

(PARI) isok(n) = issquare(n) && ispolygonal(sumdigits(n), 3); \\ Michel Marcus, Feb 27 2014

Crossrefs

Intersection of A000290 and A187744.

Cf. A000217.

Sequence in context: A255990 A104022 A061099 * A088033 A303960 A304603

Adjacent sequences: A118485 A118486 A118487 * A118489 A118490 A118491

Keyword

base,nonn

Author

Luc Stevens (lms022(AT)yahoo.com), May 05 2006

Status

approved