A154728 Products of three consecutive primes of the form 6n+1 (see A002476).

1729, 7657, 21793, 49321, 97051, 175741, 298351, 386389, 559399, 789289, 1089019, 1425829, 1924177, 2665603, 3295273, 3864241, 4631971, 5694079, 6951667, 8103877, 9363547, 10775137, 12307147, 14956219, 18091147, 21243961, 24066037

Offset

1,1

Comments

Note that a(1)=1729 is the Hardy-Ramanujan number (see taxicab numbers in A001235, A011541).

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

13, 19, 31 are three consecutive primes of the form 6n+1 and 13*19*31 = 7657. - Emeric Deutsch, Jan 21 2009

Maple

a := proc (n) if `mod`(ithprime(n), 6) = 1 then ithprime(n) else end if end proc: A := [seq(a(n), n = 1 .. 100)]: seq(A[j]*A[j+1]*A[j+2], j = 1 .. 30); # Emeric Deutsch, Jan 21 2009

Mathematica

Times@@@Partition[Select[Prime[Range[100]], IntegerQ[(#-1)/6]&], 3, 1] (* Harvey P. Dale, Jan 13 2019 *)

Crossrefs

Cf. A001235, A002476, A011541, A154716, A154717, A154729.

Sequence in context: A130859 A245671 A154716 * A286217 A337316 A338998

Adjacent sequences: A154725 A154726 A154727 * A154729 A154730 A154731

Keyword

easy,nonn

Author

Omar E. Pol, Jan 18 2009, Jan 21 2009

Extensions

Extended by Emeric Deutsch, Jan 21 2009

Status

approved