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 A343536 Positive numbers k such that the decimal expansion of k^2 appears in the concatenation of the first k positive integers. 1
 1, 428, 573, 725, 727, 738, 846, 7810, 8093, 28023, 36354, 36365, 36464, 63636, 254544, 277851, 297422, 326734, 673267, 673368, 2889810, 4545454, 4545465, 5454547, 5454646, 24275425, 29411775, 47058823, 52941178, 94117748, 146407310, 263157795, 267735365, 285714186 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A030467 is a subsequence. - Chai Wah Wu, Jun 07 2021 LINKS Chai Wah Wu, Table of n, a(n) for n = 1..116 EXAMPLE 428^2 = 183184, which appears in the concatenation of the first 428 positive integers at 183,184, i.e., (183184), so 428 is a term. 725^2 = 525625, which appears in the concatenation of the first 725 positive integers at 255,256,257, i.e., 25(525625)7, so 725 is a term. MATHEMATICA Select[Range@1000, StringContainsQ[""<>ToString/@Range@#, ToString[#^2]]&] (* Giorgos Kalogeropoulos, Apr 24 2021 *) PROG (Java) public class Oeis2 {     public static void main(String[] args) {         StringBuilder str = new StringBuilder();         long n = 1;         while (true) {             str.append(n);             if (str.indexOf(String.valueOf(n * n)) >= 0) {                 System.out.print(n + ", ");             }             n++;         }     } } (PARI) f(n) = my(s=""); for(k=1, n, s=Str(s, k)); s; \\ from A007908 isok(k) = #strsplit(f(k), Str(k^2)) > 1; \\ Michel Marcus, May 02 2021 (Python) A343536_list, k, s = [], 1, '1' while k < 10**6:     if str(k**2) in s:         A343536_list.append(k)     k += 1     s += str(k) # Chai Wah Wu, Jun 06 2021 CROSSREFS Cf. A007908, A030467, A259379. Sequence in context: A235217 A236383 A224668 * A030467 A253505 A173798 Adjacent sequences:  A343533 A343534 A343535 * A343537 A343538 A343539 KEYWORD nonn,base AUTHOR John R Phelan, Apr 18 2021 EXTENSIONS More terms from Jinyuan Wang, Apr 30 2021 STATUS approved

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Last modified September 23 20:42 EDT 2021. Contains 347617 sequences. (Running on oeis4.)