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 A080343 a(n) = round(sqrt(2*n)) - floor(sqrt(2*n)). 3
 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Chai Wah Wu, Table of n, a(n) for n = 0..10000 FORMULA Runs are 0^1, 0^1, 0^2 1, 0^2 1, 0^3 1^2, 0^3 1^2, 0^4 1^3, 0^4 1^3, ... a(n) = 1 iff n >= 4 and n is in the interval [t_k + 1, ..., t_k + floor(k/2)] for some k >= 2, where t_k = k*(k+1)/2 is a triangular number. a(n) = A023969(2*n). - Michel Marcus, Aug 19 2016 PROG (Python) from gmpy2 import isqrt_rem def A080343(n):     i, j = isqrt_rem(2*n)     return int(4*(j-i) >= 1) # Chai Wah Wu, Aug 16 2016 CROSSREFS Cf. A023969, A080352. Sequence in context: A341999 A118685 A244063 * A011664 A179831 A094091 Adjacent sequences:  A080340 A080341 A080342 * A080344 A080345 A080346 KEYWORD nonn AUTHOR N. J. A. Sloane, Mar 20 2003 STATUS approved

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Last modified June 23 07:38 EDT 2021. Contains 345395 sequences. (Running on oeis4.)