A350628 -id:A350628 - cp's OEIS frontend

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

Robert G. Wilson v, Dec 21 2000

nonn

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

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} ]

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

A350957 Number of ways to write 2*n as 3^i (i >= 0) plus a prime.

Original entry on oeis.org

0, 1, 2, 2, 1, 2, 3, 2, 1, 3, 2, 1, 2, 1, 2, 4, 2, 0, 3, 3, 1, 3, 3, 1, 3, 1, 1, 3, 1, 1, 3, 2, 0, 3, 3, 1, 3, 2, 0, 3, 2, 2, 3, 3, 1, 3, 2, 0, 4, 3, 1, 3, 3, 1, 5, 3, 1, 3, 2, 0, 2, 2, 0, 3, 2, 1, 3, 2, 1, 5, 2, 0, 1, 2, 1, 3, 3, 0, 3, 3, 0, 3, 3, 1, 2, 1, 1, 3, 2, 1, 4, 3, 0, 2, 3

Offset: 1

N. J. A. Sloane, Feb 05 2022

nonn

Cf. A006285, A058517, A350628-A350630, A350958, A282432.

a(n) = A282432(2*n). - R. J. Mathar, Mar 07 2022

A350630 Positive numbers k such that 2k cannot be written as 3^i (i >= 1) plus a prime.

Original entry on oeis.org

1, 2, 9, 12, 18, 21, 24, 27, 30, 33, 36, 39, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99, 102, 105, 108, 111, 114, 117, 120, 126, 129, 132, 135, 138, 141, 144, 147, 150, 153, 156, 159, 162, 164, 165, 168, 171, 174, 177, 180, 183, 186, 189, 192

Offset: 1

N. J. A. Sloane, Feb 05 2022

nonn

A350629 divided by 2.

Cf. A006285, A058517, A350628, A350629, A350957, A350958.

A350958 Positive numbers k such that 2k cannot be written as 3^i (i >= 0) plus a prime.

Original entry on oeis.org

1, 18, 33, 39, 48, 60, 63, 72, 78, 81, 93, 102, 105, 108, 111, 138, 144, 150, 153, 162, 164, 165, 168, 171, 183, 186, 189, 198, 204, 207, 213, 219, 228, 237, 243, 249, 258, 264, 267, 270, 273, 276, 281, 288, 291, 303, 306, 312, 315, 318, 333, 336, 345, 348, 354, 357

Offset: 1

N. J. A. Sloane, Feb 05 2022

nonn

A058517 halved.

Cf. A006285, A058517, A350628-A350630, A350957.

A350629 Positive even numbers that cannot be written as 3^i (i >= 1) plus a prime.

Original entry on oeis.org

2, 4, 18, 24, 36, 42, 48, 54, 60, 66, 72, 78, 90, 96, 102, 108, 114, 120, 126, 132, 138, 144, 150, 156, 162, 168, 174, 180, 186, 192, 198, 204, 210, 216, 222, 228, 234, 240, 252, 258, 264, 270, 276, 282, 288, 294, 300, 306, 312, 318, 324, 328, 330, 336, 342, 348, 354, 360, 366

Offset: 1

N. J. A. Sloane, Feb 05 2022

nonn

Indices of zeros in A350628 multiplied by 2.

Cf. A006285, A058517, A350628, A350630, A350957, A350958.

cp's OEIS Frontend

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

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A350957 Number of ways to write 2*n as 3^i (i >= 0) plus a prime.

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A350630 Positive numbers k such that 2k cannot be written as 3^i (i >= 1) plus a prime.

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A350958 Positive numbers k such that 2k cannot be written as 3^i (i >= 0) plus a prime.

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A350629 Positive even numbers that cannot be written as 3^i (i >= 1) plus a prime.

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Author

Keywords

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