

A001149


A selfgenerating sequence: a(1)=1, a(2)=2, a(n+1) chosen so that a(n+1)a(n1) is the first number not obtainable as a(j)a(i) for 1<=i<j<=n.
(Formerly M0689 N0254)


18



1, 2, 3, 5, 8, 13, 17, 26, 34, 45, 54, 67, 81, 97, 115, 132, 153, 171, 198, 228, 256, 288, 323, 357, 400, 439, 488, 530, 581, 627, 681, 732, 790, 843, 908, 963, 1029, 1085, 1152, 1213, 1284, 1346, 1418, 1484, 1561, 1630, 1710, 1785, 1867, 1945, 2034, 2116
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OFFSET

1,2


REFERENCES

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).


LINKS

Manfred Scheucher, Table of n, a(n) for n = 1..2000
R. K. Guy, The Second Strong Law of Small Numbers, Math. Mag, 63 (1990), no. 1, 320.
R. K. Guy, The Second Strong Law of Small Numbers, Math. Mag, 63 (1990), no. 1, 320. [Annotated scanned copy]
R. K. Guy and N. J. A. Sloane, Correspondence, 1988.
N. J. A. Sloane, Handwritten notes on SelfGenerating Sequences, 1970 (note that A1148 has now become A005282)
Manfred Scheucher, Python Script


CROSSREFS

Cf. A005282, A054540.
Sequence in context: A070217 A256121 A308869 * A144117 A081612 A301754
Adjacent sequences: A001146 A001147 A001148 * A001150 A001151 A001152


KEYWORD

nonn


AUTHOR

N. J. A. Sloane


EXTENSIONS

Description corrected and moved to name line by Franklin T. AdamsWatters, Nov 01 2009
More terms from Manfred Scheucher, Jul 01 2015


STATUS

approved



