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 A128201 Union of positive squares and the odd numbers. 6
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 OFFSET 1,2 COMMENTS Range of A128200. Positive numbers n such that n^((1 + n)/2) is an integer. - Gionata Neri, May 07 2016 LINKS R. Zumkeller, Table of n, a(n) for n = 1..10000 FORMULA a(n) = f(n,1,1,2) where f(n,i,m,x) = if i=n then m else if m+1=x^2 then f(n,i+1,m+1,x) else if m+1>x^2 then f(n,i+1,m+1,x+2) else f(n,i+1,m+2,x). Set R = 2n-round(sqrt(2n)), then a(n) = R+sign(frac(sqrt(R)))*(not(R mod 2)). - Gerald Hillier, Apr 16 2015 MATHEMATICA f[n_] := Block[{s = Range[n]^2, t}, Union[s, Range[1, Last@ s, 2]] // Sort]; f@ 12 (* Michael De Vlieger, Apr 16 2015 *) PROG (PARI) A128201(n)=!(bittest(n=2*n-round(sqrt(2*n)), 0)||issquare(n))+n \\ Based on Hiliers's formula. - M. F. Hasler, Apr 19 2015 (PARI) is_A128201(n)=bittest(n, 0)||issquare(n) \\ M. F. Hasler, Apr 19 2015 CROSSREFS Partial sums given by A157130. - Gerald Hillier, Feb 25 2009 See A176693 for the union of even numbers and the squares. - M. F. Hasler, Apr 19 2015 Sequence in context: A190941 A284752 A161153 * A233514 A096262 A193339 Adjacent sequences:  A128198 A128199 A128200 * A128202 A128203 A128204 KEYWORD nonn,easy AUTHOR Reinhard Zumkeller, Mar 04 2007 STATUS approved

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Last modified October 23 16:15 EDT 2018. Contains 316529 sequences. (Running on oeis4.)