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 A327496 a(n) = a(n - 1) * 4^r where r = valuation(n, 2) if 4 divides n else r = (n mod 2) + 1; a(0) = 1. The denominators of A327495. 2
 1, 16, 64, 1024, 16384, 262144, 1048576, 16777216, 1073741824, 17179869184, 68719476736, 1099511627776, 17592186044416, 281474976710656, 1125899906842624, 18014398509481984, 4611686018427387904, 73786976294838206464, 295147905179352825856, 4722366482869645213696 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Table of n, a(n) for n=0..19. FORMULA a(n) = denominator(r(n)) where r(n) = Sum_{j=0..n} j!^2 / (2^j*floor(j/2))^4. a(n) = 4^A327492(n). - Kevin Ryde, May 31 2022 MAPLE A327496 := n -> denom(add(j!^2 / (2^j*iquo(j, 2)!)^4, j=0..n)): seq(A327496(n), n=0..19); PROG (SageMath) @cached_function def A327496(n): if n == 0: return 1 r = valuation(n, 2) if 4.divides(n) else n % 2 + 1 return 4^r * A327496(n-1) print([A327496(n) for n in (0..19)]) (PARI) a(n) = 1 << (4*n - 2*hammingweight(n>>1)); \\ Kevin Ryde, May 31 2022 CROSSREFS Cf. A327491, A327492, A327493, A327494, A327495. Cf. A056982. Sequence in context: A203281 A255576 A065404 * A330824 A189806 A222748 Adjacent sequences: A327493 A327494 A327495 * A327497 A327498 A327499 KEYWORD nonn,easy AUTHOR Peter Luschny, Sep 29 2019 STATUS approved

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Last modified August 15 19:07 EDT 2024. Contains 375173 sequences. (Running on oeis4.)