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 A246560 Least number k such that k concatenated with n is a square, or 0 if no such k exists. 0
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) = 0 if and only if n is in A246448. LINKS 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

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Last modified May 5 23:41 EDT 2021. Contains 343579 sequences. (Running on oeis4.)