A179679 Smaller of each pair of consecutive primes which sum to a practical number.

3, 5, 7, 11, 13, 17, 19, 29, 37, 41, 43, 47, 53, 59, 61, 71, 79, 97, 101, 103, 107, 113, 137, 139, 149, 151, 157, 163, 167, 173, 179, 191, 193, 197, 223, 227, 229, 239, 257, 263, 269, 277, 283, 293, 311, 313, 317, 337, 347, 349, 359, 367, 397, 401, 409, 419, 431

Offset: 1

Author

Jason G. Wurtzel, Jul 24 2010

Keywords

• nonn

Comments

Complement is: 2, 23, 31, 67, 73, 83, 89, 109, 127, 131, 181, 199, 211, ..., . - Robert G. Wilson v, Aug 03 2010

Examples

			19 is a term because the next consecutive prime is 23, and 19 + 23 = 42, which is a practical number.
		

Crossrefs

Cf. A000040, A005153.

Programs

Mathematica

PracticalQ[n_] := Module[{f, p, e, prod = 1, ok = True}, If[n < 1 || (n > 1 && OddQ[n]), False, If[n == 1, True, f = FactorInteger[n]; {p, e} = Transpose[f]; Do[If[p[[i]] > 1 + DivisorSigma[1, prod], ok = False; Break[]]; prod = prod*p[[i]]^e[[i]], {i, Length[p]}]; ok]]]; First@# & /@ Select[ Partition[ Prime@ Range@ 85, 2, 1], PracticalQ[Plus @@ # ] &] (* Robert G. Wilson v, Aug 03 2010 *)

Extensions

More terms from Robert G. Wilson v, Aug 03 2010