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Search: id:A135464
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| A135464 |
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Numbers n with property that for each single digit d of the base 3 expansion of n, we can also see the base 3 expansion of d^2 as a substring. Also n may not contain any 0 digits. |
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+0
2
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| 1, 11, 111, 112, 211, 1111, 1112, 1121, 1122, 1211, 2111, 2112, 2211, 11111, 11112, 11121, 11122, 11211, 11212, 11221, 11222, 12111, 12112, 12211, 21111, 21112, 21121, 21122, 21211, 22111, 22112, 22211, 111111, 111112, 111121
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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The base 3 expansion of n may only contain 1's and 2's, and if a 2 is present then 11 must also be present. These are the only restrictions.
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LINKS
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David Applegate, Table of n, a(n) for n = 1..300
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PROGRAM
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(AWK, from David Applegate) awk 'function g(s, v, n){if (n==0){if (index(s, "2")==0||index(s, "11")>0)print v; }else{g(s "1", v*3+1, n-1); g(s "2", v*3+2, n-1); }}BEGIN{for (i=1; i<=8; i++)g("", 0, i); }'
For C++ program see the Applegate link in A135463.
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CROSSREFS
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Base 3 analogue of A134962. Cf. A135465.
Sequence in context: A061493 A093788 A098759 this_sequence A083278 A039987 A039989
Adjacent sequences: A135461 A135462 A135463 this_sequence A135465 A135466 A135467
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KEYWORD
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nonn,base,easy
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AUTHOR
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David Applegate and njas, Feb 07 2008
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