A188499 Intersection of A089633 and A188341.

1, 2, 5, 7, 23, 239

Offset: 0

Author

Vladimir Shevelev, Apr 02 2011

Keywords

• nonn
• base
• more

Comments

Binomial coefficient predictors in both bases 2 and 3 (for definition, see paper in link).

Next term is > 5*10^300, if it exists.

Links

• V. Shevelev, Binomial Coefficient Predictors, Journal of Integer Sequences, Vol. 14 (2011), Article 11.2.8.

Crossrefs

Cf. A089633, A188341.

Programs

Mathematica

aQ[n_]:= DigitCount[n, 2, 0] < 2 && DigitCount[n, 3, 0] == 0 && DigitCount[n, 3, 1] < 2; Select[Range[1000], aQ] (* Amiram Eldar, Dec 10 2018 *)

PARI

isok2(n) = my(b=binary(n)); #select(x->(x==0), b) <= 1; \\ A089633
isok3(n) = my(d=digits(n, 3)); (#select(x->(x==0), d) == 0) && (#select(x->(x==1), d) <= 1); \\ A188341
isok(n) = isok2(n) && isok3(n); \\ Michel Marcus, Dec 10 2018