A066564 Numbers that when incremented by the sum of their digits produce a square.
0, 2, 8, 17, 27, 38, 72, 86, 135, 161, 179, 216, 245, 275, 315, 347, 432, 467, 521, 558, 614, 662, 720, 770, 830, 882, 944, 998, 1016, 1080, 1145, 1220, 1278, 1355, 1433, 1512, 1583, 1664, 1746, 1829, 1922, 1998, 2016, 2111, 2189, 2286, 2384, 2483, 2583
Offset: 1
Examples
179 is in the sequence because 179 + sum of digits of 179 = 179 + 17 = 196 which is a perfect square. - _Indranil Ghosh_, Feb 10 2017
Links
- Indranil Ghosh, Table of n, a(n) for n = 1..11130 (terms 1..1000 from Harry J. Smith)
Programs
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Magma
[n: n in [0..3*10^3] | IsSquare(&+Intseq(n)+n)]; // Vincenzo Librandi, Jan 15 2016
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Mathematica
Select[Range[0,2600],IntegerQ[Sqrt[#+Total[IntegerDigits[#]]]]&] (* Harvey P. Dale, May 19 2012 *)
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PARI
digitsum(n) = local(s, d); s = 0; while(n>0, d = divrem(n, 10); n = d[1]; s = s+d[2]); s a066564(m) = local(n); for(n = 0, m, if(issquare(n+digitsum(n)), print1(n, ", "))) a066564(10000)
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PARI
isok(n) = issquare(n + sumdigits(n)); \\ Michel Marcus, Jan 15 2016
Extensions
More terms from Jason Earls, Dec 20 2001