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 A069020 a(1) = 1; a(n) = smallest number of the form k*a(n-1) +1 divisible by n^2. 0
 1, 4, 9, 64, 1025, 19476, 331093, 993280, 73502721, 1396551700, 64241378201, 6616861954704, 853575192156817, 16217928650979524, 1232562577474443825, 57930441141298859776, 3475826468477931586561, 79944008774992426490904 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Terms from Robert G. Wilson v. LINKS MATHEMATICA a[1] = 1; a[n_] := a[n] = Block[{k = 1}, While[ !IntegerQ[(k*a[n - 1] + 1)/n^2], k++ ]; Return[k*a[n - 1] + 1]]; Table[a[n], {n, 1, 19}] (* Robert G. Wilson v *) CROSSREFS Sequence in context: A055859 A162991 A062926 * A220189 A122956 A041777 Adjacent sequences:  A069017 A069018 A069019 * A069021 A069022 A069023 KEYWORD nonn AUTHOR Amarnath Murthy, Apr 02 2002 STATUS approved

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Last modified November 27 19:06 EST 2021. Contains 349394 sequences. (Running on oeis4.)