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 A127707 Number of commutative rings with 1 containing n elements. 12
 1, 1, 1, 4, 1, 1, 1, 10, 4, 1, 1, 4, 1, 1, 1, 37, 1, 4, 1, 4, 1, 1, 1, 10, 4, 1, 11, 4, 1, 1, 1, 109, 1, 1, 1, 16, 1, 1, 1, 10, 1, 1, 1, 4, 4, 1, 1, 37, 4, 4, 1, 4, 1, 11, 1, 10, 1, 1, 1, 4, 1, 1, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS Is this a multiplicative function? Answer: yes! See the Eric M. Rains link for a proof for the result for all unital rings; restricting to commutative rings does not affect the essence of the proof. - Jianing Song, Feb 02 2020 LINKS Table of n, a(n) for n=1..63. C. Noebauer, Home page and Table of numbers of small rings [Archived copies from web.archive.org] Eric M. Rains, The number of unital rings with n elements is a multiplicative function of n. FORMULA a(n) = A037291(n) - A127708(n). - Bernard Schott, Apr 19 2022 CROSSREFS Cf. A037289, A037291, A127708, A027623, A307000, A341202. Sequence in context: A303278 A222639 A184729 * A113196 A037291 A222317 Adjacent sequences: A127704 A127705 A127706 * A127708 A127709 A127710 KEYWORD more,nice,nonn,mult AUTHOR Hugues Randriam (randriam(AT)enst.fr), Jan 24 2007 EXTENSIONS Keyword 'mult' added by Jianing Song, Feb 02 2020 a(32)-a(63) using Nöbauer's data added by Andrey Zabolotskiy, Apr 18 2022 a(32) = 109 corrected by Bernard Schott, Apr 19 2022 STATUS approved

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Last modified February 27 09:53 EST 2024. Contains 370377 sequences. (Running on oeis4.)