A135464 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.

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

Offset

1,2

Comments

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.

Links

David Applegate, Table of n, a(n) for n = 1..300

Prog

(AWK) 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); }' # David Applegate
(C++) // See the Applegate link in A135463.

Crossrefs

Base-3 analog of A134962. Cf. A135465.

Sequence in context: A098759 A273977 A358441 * A231872 A308365 A083278

Adjacent sequences: A135461 A135462 A135463 * A135465 A135466 A135467

Keyword

nonn,base,easy

Author

David Applegate and N. J. A. Sloane, Feb 07 2008

Status

approved