A284293 Numbers using only digits 1 and 6.

1, 6, 11, 16, 61, 66, 111, 116, 161, 166, 611, 616, 661, 666, 1111, 1116, 1161, 1166, 1611, 1616, 1661, 1666, 6111, 6116, 6161, 6166, 6611, 6616, 6661, 6666, 11111, 11116, 11161, 11166, 11611, 11616, 11661, 11666, 16111, 16116, 16161, 16166, 16611, 16616

Offset

1,2

Comments

Product of digits of n is a power of 6; subsequence of A276038.

Prime terms are in A020454.

Links

Alois P. Heinz, Table of n, a(n) for n = 1..16382

Mathematica

Join @@ (FromDigits /@ Tuples[{1, 6}, #] & /@ Range[5]) (* Giovanni Resta, Mar 25 2017 *)

Prog

(Magma) [n: n in [1..20000] | Set(IntegerToSequence(n, 10)) subset {1, 6}];
(Python)
def A284293(n): return 5*int(bin(n+1)[3:])+(10**((n+1).bit_length()-1)-1)//9 # Chai Wah Wu, Jun 28 2025

Crossrefs

Cf. Numbers using only digits 1 and k for k = 0 and k = 2 - 9: A007088 (k = 0), A007931 (k = 2), A032917 (k = 3), A032822 (k = 4) , A276037 (k = 5), this sequence (k = 6), A276039 (k = 7), A213084 (k = 8), A284294 (k = 9).

Sequence in context: A024730 A024952 A278833 * A117800 A118847 A111256

Adjacent sequences: A284290 A284291 A284292 * A284294 A284295 A284296

Keyword

nonn,base

Author

Jaroslav Krizek, Mar 25 2017

Status

approved