A246560 Least number k such that k concatenated with n is a square, or 0 if no such k exists.

8, 0, 0, 6, 2, 1, 0, 0, 4, 0, 0, 0, 0, 0, 0, 21, 0, 0, 0, 0, 1, 0, 0, 3, 2, 0, 0, 0, 5, 0, 0, 0, 0, 0, 0, 19, 0, 0, 0, 0, 4, 0, 0, 1, 0, 0, 0, 0, 18, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 3, 0, 0, 17, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 0, 16, 0, 0, 4, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 8, 0, 0, 0, 23

Offset

1,1

Comments

a(n) = 0 if and only if n is in A246448.

Links

Table of n, a(n) for n=1..104.

Example

The smallest square ending with 5 is 25, so a(5) = 2.

Prog

(PARI)
b(n)=v=[]; for(k=10^(n-1), 10^n, v=concat(v, k^2%10^n)); v=vecsort(v, , 8); v
w=[]; for(k=1, 250, d=digits(k); if(vecsearch(b(#d), k), w=concat(w, k))); w=vecsort(w, , 8); w;
a(n)=if(!vecsearch(w, n), return(0)); if(vecsearch(w, n), j=1; s=Str(n); while(!issquare(eval(concat(Str(j), s))), j++); return(j))
vector(200, n, a(n))

Crossrefs

Cf. A000290, A071176, A246448.

Sequence in context: A157244 A154191 A010771 * A199064 A280653 A274413

Adjacent sequences: A246557 A246558 A246559 * A246561 A246562 A246563

Keyword

nonn,base

Author

Derek Orr, Aug 29 2014

Status

approved