cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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

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%I A154728 #11 Jan 13 2019 13:10:33
%S A154728 1729,7657,21793,49321,97051,175741,298351,386389,559399,789289,
%T A154728 1089019,1425829,1924177,2665603,3295273,3864241,4631971,5694079,
%U A154728 6951667,8103877,9363547,10775137,12307147,14956219,18091147,21243961,24066037
%N A154728 Products of three consecutive primes of the form 6n+1 (see A002476).
%C A154728 Note that a(1)=1729 is the Hardy-Ramanujan number (see taxicab numbers in A001235, A011541).
%H A154728 Harvey P. Dale, <a href="/A154728/b154728.txt">Table of n, a(n) for n = 1..1000</a>
%e A154728 13, 19, 31 are three consecutive primes of the form 6n+1 and 13*19*31 = 7657. - _Emeric Deutsch_, Jan 21 2009
%p A154728 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
%t A154728 Times@@@Partition[Select[Prime[Range[100]],IntegerQ[(#-1)/6]&],3,1] (* _Harvey P. Dale_, Jan 13 2019 *)
%Y A154728 Cf. A001235, A002476, A011541, A154716, A154717, A154729.
%K A154728 easy,nonn
%O A154728 1,1
%A A154728 _Omar E. Pol_, Jan 18 2009, Jan 21 2009
%E A154728 Extended by _Emeric Deutsch_, Jan 21 2009