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 A240754 Numbers k with digit_sum(k*k) - 1 = digit_sum((k+1)*(k+1)). 4
 8, 26, 53, 98, 107, 143, 161, 170, 179, 188, 224, 233, 242, 260, 269, 278, 287, 296, 350, 368, 386, 404, 413, 431, 449, 476, 494, 503, 539, 548, 557, 584, 593, 629, 638, 647, 674, 683, 737, 746, 773, 791, 818, 827, 863, 872, 908, 926, 944, 998, 1007, 1043 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS A240752(a(n)) = 0. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 PROG (Haskell) import Data.List (elemIndices) a240754 n = a240754_list !! (n-1) a240754_list = elemIndices (-1) a240752_list (Python) def ds(n): return sum(map(int, str(n))) def ok(n): return ds(n*n) - 1 == ds((n+1)*(n+1)) print(list(filter(ok, range(1044)))) # Michael S. Branicky, Aug 26 2021 CROSSREFS Cf. A202089, A239878, A004159, A007953, A000290. Sequence in context: A138502 A143894 A126176 * A074238 A126264 A347677 Adjacent sequences:  A240751 A240752 A240753 * A240755 A240756 A240757 KEYWORD nonn,base AUTHOR Reinhard Zumkeller, Apr 12 2014 STATUS approved

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Last modified January 23 07:50 EST 2022. Contains 350510 sequences. (Running on oeis4.)