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

Author

Jonathan Vos Post, Nov 24 2012

Keywords

• nonn
• easy

Comments

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

Examples

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

Links

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

Crossrefs

Cf. A000040, A051037, A219528.

Programs

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 *)

Formula

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

Extensions

Corrected by T. D. Noe, Nov 25 2012