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A001375
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Relational systems on n nodes.
(Formerly M4589 N1958)
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0
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8, 2080, 22386176, 11728394650624, 314824619911446167552, 450720219711043642520721817600, 35398008262453198128587489274987385192448, 155682086692129060007763454017522652304844346252853248
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OFFSET
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1,1
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REFERENCES
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W. Oberschelp, "Strukturzahlen in endlichen Relationssystemen," in Contributions to Mathematical Logic (Proceedings 1966 Hanover Colloquium), pp. 199-213, North-Holland Publ., Amsterdam, 1968.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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Table of n, a(n) for n=1..8.
W. Oberschelp, Strukturzahlen in endlichen Relationssystemen, in Contributions to Mathematical Logic (Proceedings 1966 Hanover Colloquium), pp. 199-213, North-Holland Publ., Amsterdam, 1968. [Annotated scanned copy]
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FORMULA
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a(n) = Sum_{1*s_1+2*s_2+...=n}(fix A[s_1, s_2, ...]/ (1^s_1*s_1!*2^s_2*s_2!*...)) where fix A[s_1, s_2, ...] = 8^Sum_{i, j>=1} (gcd(i,j)*s_i*s_j). - Sean A. Irvine, Nov 20 2016
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CROSSREFS
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Sequence in context: A300107 A139298 A004819 * A281651 A189308 A300597
Adjacent sequences: A001372 A001373 A001374 * A001376 A001377 A001378
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane
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EXTENSIONS
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More terms from Sean A. Irvine, Nov 20 2016
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STATUS
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approved
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