A146091 - OEIS

A146091

a(n) = 3*A146085(n) - 2.

1, 10, 19, 82, 91, 100, 163, 172, 181, 730, 739, 748, 811, 820, 829, 892, 901, 910, 1459, 1468, 1477, 1540, 1549, 1558, 1621, 1630, 1639, 6562, 6571, 6580, 6643, 6652, 6661, 6724, 6733, 6742, 7291, 7300, 7309, 7372, 7381, 7390, 7453, 7462, 7471, 8020, 8029, 8038, 8101, 8110, 8119

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OFFSET

1,2

COMMENTS

Positive integers such that for every integer m==4 (mod 9) there exists a unique representation of m as a sum of the form a(l)+3a(s).

LINKS

Table of n, a(n) for n=1..51.

PROG

(PARI) isa(n) = {my(d=Vecrev(digits(n, 3)), k=3); while (k <= #d, if (d[k], return (0)); k += 2; ); d[1] == 1; } \\ A146085

isok(n) = !((n+2) % 3) && isa((n+2)/3); \\ Michel Marcus, Dec 09 2018

CROSSREFS

Cf. A146085, A146087, A145812, A145818.