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 A053676 Let Oc(n) = A005900(n) = n-th octahedral number. Consider all integer triples (i,j,k), j >= k > 0, with Oc(i) = Oc(j)+Oc(k), ordered by increasing i; sequence gives i values. 5
 7, 41, 465, 2732, 3005, 20648, 48125, 94396, 129299, 282931, 789281, 835050, 1241217, 1292143, 1521647, 1603655, 2756953, 4847702, 5128447, 6242598 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(21) > 10^7. - Donovan Johnson, Sep 29 2010 REFERENCES Pollock, F. "On the Extension of the Principle of Fermat's Theorem of the Polygonal Numbers to the Higher Orders of Series Whose Ultimate Differences Are Constant. With a New Theorem Proposed, Applicable to All the Orders." Abs. Papers Commun. Roy. Soc. London 5, 922-924, 1843-1850. Dickson, L. E., History of the Theory of Numbers, Vol. 2: Diophantine Analysis. New York: Dover, 2005, cites the Pollock reference. LINKS EXAMPLE Oc(7) = 231 = Oc(6) + Oc(5); Oc(41) = 45961 = Oc(40) + Oc(17); Oc(465) = 67029905 = Oc(454) + Oc(191) CROSSREFS Cf. A005900, A053677 (j values), A053678 (k values). Sequence in context: A290044 A209113 A146991 * A002701 A057006 A144747 Adjacent sequences:  A053673 A053674 A053675 * A053677 A053678 A053679 KEYWORD nice,nonn AUTHOR Klaus Strassburger (strass(AT)ddfi.uni-duesseldorf.de), Feb 16 2000 EXTENSIONS More terms from Larry Reeves (larryr(AT)acm.org), May 07 2001 a(13)-a(16) from Donovan Johnson, Jun 21 2010 a(17)-a(20) from Donovan Johnson, Sep 29 2010 STATUS approved

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Last modified October 18 02:23 EDT 2019. Contains 328135 sequences. (Running on oeis4.)