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 A162887 Odd nonprimes in an alternating 1-based sum up to some odd nonprime. 0
 15, 33, 39, 51, 69, 75, 87, 105, 117, 123, 129, 141, 159, 177, 183, 189, 195, 201, 213, 219, 231, 243, 249, 255, 267, 279, 285, 303, 309, 315, 321, 327, 333, 339, 357, 369, 375, 381, 393, 399, 411, 429, 435, 447, 453, 459, 465, 483, 489, 495, 501, 513, 519 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Define the alternating sum S(u) = sum_{k=0..u} (1-(-1)^k*k) = A064455(u+1) as in A162886. Evaluate the sum with upper limits u= 1,9, 15, 21... from A014076, and add S(u) to this sequence here whenever it is itself a member of A014076. LINKS EXAMPLE The sequence S(u) = 3, 15, 24, 33, 39, 42, 51, 54, 60, 69, ... is generated by u = 1, 9, 15, 21, ... The first S-term, 3, is prime, and therefore not added to the sequence. The second S-term, 15, is an odd nonprime and added to the sequence. The third, 24, is even and not added to the sequence. CROSSREFS Cf. A014076. Sequence in context: A141230 A140608 A085371 * A231370 A246755 A212311 Adjacent sequences:  A162884 A162885 A162886 * A162888 A162889 A162890 KEYWORD nonn,less AUTHOR Juri-Stepan Gerasimov, Jul 16 2009 EXTENSIONS 3 removed by R. J. Mathar, Aug 27 2009 STATUS approved

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Last modified May 6 05:03 EDT 2021. Contains 343580 sequences. (Running on oeis4.)