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A340377 Numbers k such that there are no 2-digits in the ternary expansion of A048673(k). 5
1, 3, 5, 9, 13, 17, 19, 21, 35, 47, 53, 59, 67, 71, 73, 91, 93, 95, 121, 123, 129, 143, 145, 157, 163, 173, 175, 179, 207, 211, 229, 233, 239, 255, 267, 291, 297, 299, 321, 327, 351, 355, 371, 381, 405, 413, 437, 451, 477, 479, 485, 487, 499, 503, 505, 523, 527, 541, 547, 549, 557, 595, 643, 645, 647, 661, 691, 701 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

All terms are odd, because A048673(2n) = 3*A048673(n) - 1, which forces the least significant digit in the ternary expansion of A048673(2n) to be "2".

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..20000

Index entries for sequences computed from indices in prime factorization

PROG

(PARI)

A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From A003961

A048673(n) = (A003961(n)+1)/2;

A289814(n) = { my (d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==2, 1, 0)), 2); } \\ From A289814

A291759(n) = A289814(A048673(n));

isA340377(n) = (0==A291759(n));

CROSSREFS

Positions of zeros in A291759 and in A340379. Positions of ones in A340382.

Cf. A048673, A340376.

Sequence in context: A286058 A342474 A076052 * A050556 A138008 A063954

Adjacent sequences:  A340374 A340375 A340376 * A340378 A340379 A340380

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jan 15 2021

STATUS

approved

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Last modified September 19 19:41 EDT 2021. Contains 347564 sequences. (Running on oeis4.)