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 A238237 Numbers which when chopped into two parts with equal length, added and squared result in the same number. 8
 81, 2025, 3025, 9801, 494209, 998001, 24502500, 25502500, 52881984, 60481729, 99980001, 6049417284, 6832014336, 9048004641, 9999800001, 101558217124, 108878221089, 123448227904, 127194229449, 152344237969, 213018248521, 217930248900, 249500250000, 250500250000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Yet another variant of the Kaprekar numbers A006886. - N. J. A. Sloane, Aug 06 2017 From Bernard Schott, Jan 21 2022: (Start) Three subsequences: -> {(10^m-1)^2, m >= 1} = A059988 \ {0}; see example 9801. -> {(10^m-1)^2 * 10^(2*m) / 4, m >= 1} = A350869 \ {0}; see example 2025. -> {(10^m+1)^2 * 10^(2*m) / 4, m >= 1} = A038544 \ {1}, see example 3025. (End) LINKS Rémy Sigrist, Table of n, a(n) for n = 1..25000 FORMULA a(n) = A290449(n)^2. - Bernard Schott, Jan 20 2022 EXAMPLE 2025 = (20 + 25)^2, so 2025 is in the sequence. 3025 = (30 + 25)^2, so 3025 is in the sequence. 9801 = (98 + 01)^2, so 9801 is in the sequence. PROG (PARI) forstep(m=1, 7, 2, p=10^((m+1)/2); for(n=10^m, 10^(m+1)-1, d=lift(Mod(n, p)); if(((n-d)/p+d)^2==n, print1(n, ", ")))); CROSSREFS Subsequence of A102766. Subsequence: A350870. Cf. A006886, A038544, A059988, A350869. For square roots see A290449. Sequence in context: A253448 A205978 A037211 * A350870 A282861 A237376 Adjacent sequences:  A238234 A238235 A238236 * A238238 A238239 A238240 KEYWORD nonn,base AUTHOR Arkadiusz Wesolowski, Feb 20 2014 EXTENSIONS a(12)-a(24) from Donovan Johnson, Feb 22 2014 STATUS approved

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Last modified July 3 20:11 EDT 2022. Contains 355058 sequences. (Running on oeis4.)