A045863 Numbers whose square has initial digit '9'.

3, 30, 31, 95, 96, 97, 98, 99, 300, 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 311, 312, 313, 314, 315, 316, 949, 950, 951, 952, 953, 954, 955, 956, 957, 958, 959, 960, 961, 962, 963, 964, 965, 966, 967, 968, 969, 970, 971, 972, 973, 974, 975, 976

Offset: 1

Author

Jeff Burch

Keywords

• nonn
• base
• easy

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A045793.

Programs

Mathematica

id9[n_]:=Module[{min=Floor[Sqrt[9*10^n]],max=Floor[Sqrt[10*10^n]]}, Select[ Range[ min,max], First[IntegerDigits[#^2]]==9&]]; Flatten[ Table[ id9[n],{n,0,5}]] (* Harvey P. Dale, May 29 2013 *)

PARI

list(lim)=my(v=List()); for(d=1,2*#digits(lim\=1), for(n=sqrtint(9*10^(d-1)-1)+1, min(sqrtint(10^d-1), lim), listput(v, n))); Vec(v) \\ Charles R Greathouse IV, Nov 03 2021