A058517 Positive even numbers not of the form prime + 3^x.

2, 36, 66, 78, 96, 120, 126, 144, 156, 162, 186, 204, 210, 216, 222, 276, 288, 300, 306, 324, 328, 330, 336, 342, 366, 372, 378, 396, 408, 414, 426, 438, 456, 474, 486, 498, 516, 528, 534, 540, 546, 552, 562, 576, 582, 606, 612, 624, 630, 636, 666, 672, 690

Offset

1,1

Links

Table of n, a(n) for n=1..53.

Mathematica

Do[ i = 0; l = Ceiling[ N[ Log[ 3, n ] ] ]; While[ ! PrimeQ[ n - 3^i ] && i < l, i++ ]; If[ i == l, Print[ n ] ], {n, 2, 1000, 2} ]

Prog

(PARI) isok(n) = {if (n % 2, 0, lim = log(n)/log(3); for (k=0, lim, if (isprime(n - 3^k), return (0)); ); 1; ); } \\ Michel Marcus, Feb 25 2017

Crossrefs

Cf. A006285, A156695, A350628-A350630, A350957, A350958, A282430 (subsequence).

Sequence in context: A096513 A037418 A239343 * A328963 A081310 A187298

Adjacent sequences: A058514 A058515 A058516 * A058518 A058519 A058520

Keyword

nonn

Author

Robert G. Wilson v, Dec 21 2000

Status

approved