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 A100037 Positions of occurrences of the natural numbers as a second subsequence in A100035. 21
 4, 9, 18, 31, 48, 69, 94, 123, 156, 193, 234, 279, 328, 381, 438, 499, 564, 633, 706, 783, 864, 949, 1038, 1131, 1228, 1329, 1434, 1543, 1656, 1773, 1894, 2019, 2148, 2281, 2418, 2559, 2704, 2853, 3006, 3163, 3324, 3489, 3658, 3831, 4008, 4189, 4374, 4563 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS For n > 1, A100035(a(n)) = n and A100035(m) != n for a(n-1) <= m < a(n); A100036(n) < a(n) < A100038(n) < A100039(n). LINKS Guo-Niu Han, Enumeration of Standard Puzzles, 2011. [Cached copy] Guo-Niu Han, Enumeration of Standard Puzzles, arXiv:2006.14070 [math.CO], 2020. FORMULA a(n) = 2*n^2 - n + 3 (conjectured). - Ralf Stephan, May 15 2007 EXAMPLE First terms (10 = A, 11 = B, 12 = C) of A100035(a(n)): ...1....2........3............4................5...... 1231435425165764736271879869584938291A9BA8B7A6B5A4B3A2B; a(1) = A084849(2) = 4, A100035(4) = 1; a(2) = A014107(2) = 9, A100035(9) = 2; a(3) = A033537(3) = 18, A100035(18) = 3; a(4) = A100040(4) = 31, A100035(31) = 4; a(5) = A100041(5) = 48, A100035(48) = 5. CROSSREFS Cf. A014107, A033537, A084849, A100035, A100036, A100038, A100039, A100040, A100041. Sequence in context: A301017 A008219 A008223 * A063916 A009855 A038402 Adjacent sequences:  A100034 A100035 A100036 * A100038 A100039 A100040 KEYWORD nonn AUTHOR Reinhard Zumkeller, Oct 31 2004 STATUS approved

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Last modified January 15 21:33 EST 2021. Contains 340195 sequences. (Running on oeis4.)