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 A087052 Lunar triangular numbers: 0+1+2+3+...+n, where + is lunar addition. 2
 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 29, 29, 29, 29, 29, 29, 29, 29, 29, 29, 39, 39, 39, 39, 39, 39, 39, 39, 39, 39, 49, 49, 49, 49, 49, 49, 49, 49, 49, 49, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 69, 69, 69, 69, 69, 69, 69, 69, 69, 69, 79, 79, 79, 79, 79, 79, 79, 79, 79, 79, 89, 89, 89, 89, 89, 89, 89, 89, 89, 89, 99, 99, 99, 99, 99, 99, 99, 99, 99, 99, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199, 199 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Differs from A087121 after 100 terms. If duplicates are removed we get A051885. - N. J. A. Sloane, Jan 25 2011 LINKS D. Applegate, C program for lunar arithmetic and number theory [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing] D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing] D. Applegate, M. LeBrun, N. J. A. Sloane, Dismal Arithmetic, J. Int. Seq. 14 (2011) # 11.9.8. MAPLE (Continuing from A087062) dt := proc(n) local i, t1; t1 := 0; for i from 1 to n do t1 := dadd(t1, i); od: t1; end; CROSSREFS Cf. A051885. Sequence in context: A106649 A284030 A087121 * A117241 A077557 A075517 Adjacent sequences:  A087049 A087050 A087051 * A087053 A087054 A087055 KEYWORD nonn AUTHOR Marc LeBrun and N. J. A. Sloane, Oct 19 2003 STATUS approved

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Last modified November 12 13:36 EST 2018. Contains 317109 sequences. (Running on oeis4.)