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 A362383 Number of labeled right involutory magmas with n elements. 4
 1, 1, 4, 64, 10000, 11881376, 192699928576, 36175612601171968, 116077185312503648813056, 5817168207073186596352000000000, 5962207128673051739782035558293177368576, 119898867867315010793162270409575082620582830800896, 57436979804085599487337333419576950752550097125586310052970496 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS A magma with element set X is right involutory if (xy)y = x for x,y in X. LINKS Andrew Howroyd, Table of n, a(n) for n = 0..30 FORMULA a(n) = A000085(n)^n. MAPLE b:= proc(n) b(n):= `if`(n<2, 1, b(n-1)+(n-1)*b(n-2)) end: a:= n-> b(n)^n: seq(a(n), n=0..15); # Alois P. Heinz, Apr 30 2023 PROG (PARI) \\ here b(n) is A000085(n). b(n)=sum(j=0, n\2, binomial(n, 2*j)*(2*j)!/(2^j*j!)) a(n)=b(n)^n CROSSREFS Cf. A000085, A002489 (magmas), A076016, A362382 (isomorphism classes). Sequence in context: A211214 A372813 A229867 * A051191 A120581 A146520 Adjacent sequences: A362380 A362381 A362382 * A362384 A362385 A362386 KEYWORD nonn AUTHOR Andrew Howroyd, Apr 17 2023 STATUS approved

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Last modified September 8 08:26 EDT 2024. Contains 375753 sequences. (Running on oeis4.)