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 A225376 Construct sequences P,Q,R by the rules: Q = first differences of P, R = second differences of P, P starts with 1,5,11, Q starts with 4,6, R starts with 2; at each stage the smallest number not yet present in P,Q,R is appended to R; every number appears exactly once in the union of P,Q,R. Sequence gives P. 8
 1, 5, 11, 20, 36, 60, 94, 140, 199, 272, 360, 465, 588, 730, 893, 1078, 1286, 1519, 1778, 2064, 2378, 2721, 3094, 3498, 3934, 4403, 4907, 5448, 6027, 6645, 7303, 8002, 8743, 9527, 10355, 11228 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS P can be extended for 10^6 terms, but it is not known if P,Q,R can be extended to infinity. A probabilistic argument suggests that P, Q, R are infinite. - N. J. A. Sloane, May 19 2013 Martin Gardner (see reference) states that no such triple P,Q,R of sequences exists if it is required that P(1) {} then: return NULL:     elif {h} intersect {ddh} <> {} then: return NULL:     elif {ddh} intersect {dh} <> {} then: return NULL:     else: return [h]: fi: end proc: # Christopher Carl Heckman, May 12 2013 CROSSREFS Cf. A225377, A225378, A005228, A030124, A037257. Sequence in context: A026038 A080957 A118375 * A099400 A139534 A245773 Adjacent sequences:  A225373 A225374 A225375 * A225377 A225378 A225379 KEYWORD nonn AUTHOR N. J. A. Sloane, May 12 2013, based on email from Christopher Carl Heckman, May 06 2013 EXTENSIONS Corrected and edited by Christopher Carl Heckman, May 12 2013 STATUS approved

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Last modified October 22 23:18 EDT 2018. Contains 316518 sequences. (Running on oeis4.)