A219669 Primes neighboring a 5-smooth number.

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 47, 53, 59, 61, 71, 73, 79, 89, 97, 101, 107, 109, 127, 149, 151, 163, 179, 181, 191, 193, 199, 239, 241, 251, 257, 269, 271, 359, 383, 401, 431, 433, 449, 479, 487, 499, 541, 577, 599, 601, 641, 647, 719, 751

Offset

1,1

Comments

This is to A219528 as 3-smooth numbers A003586 are to 5-smooth numbers A051037.

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

Primes INTERSECTION {2^i 3^j 5^k +/-1 for i,j,k >= 0}.

Example

a(1) = 2 = 2^0 * 3^0 * 5^0 + 1 = 2^0 * 3^1 * 5^0 - 1.

Mathematica

mx = 2^10; t5 = Select[Sort[Flatten[Table[2^i * 3^j * 5^k, {i, 0, Log[2, mx]}, {j, 0, Log[3, mx]}, {k, 0, Log[5, mx]}]]], # <= mx &]; Union[Select[t5 + 1, PrimeQ], Select[t5 - 1, PrimeQ]] (* T. D. Noe, Nov 25 2012 *)

Crossrefs

Cf. A000040, A051037, A219528.

Sequence in context: A052042 A245576 A086472 * A109611 A181325 A078133

Adjacent sequences: A219666 A219667 A219668 * A219670 A219671 A219672

Keyword

nonn,easy

Author

Jonathan Vos Post, Nov 24 2012

Extensions

Corrected by T. D. Noe, Nov 25 2012

Status

approved