|
Search: id:A091859
|
|
|
| A091859 |
|
a(1) = 2, a(n) is the least prime of the form 2k*a(n-1)+1 where 2k is the least even number not used earlier. |
|
+0
1
|
|
| 2, 5, 31, 311, 3733, 59729, 1194581, 57339889, 1605516893, 22477236503, 1933042339259, 143045133105167, 2574812395893007, 87543621460362239, 700348971682897913, 58829313621363424693, 1411903526912722192633
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
EXAMPLE
|
a(2) = 5 = 2*2+1, But a(3) = 31 though 11= 5*2 +1 is also prime.
|
|
PROGRAM
|
Contribution from Rick L. Shepherd (rshepherd2(AT)hotmail.com), Sep 08 2009: (Start)
(PARI) {a=[2]; terms=1; used=Set();
while(terms<30, k2=0; until(isprime(k2*a[terms]+1),
until(setsearch(used, k2)==0, k2=k2+2));
a=concat(a, k2*a[terms]+1); terms++; used=setunion(used, Set([k2]))); a} (End)
|
|
CROSSREFS
|
Sequence in context: A058009 A097396 A056788 this_sequence A085873 A051048 A163852
Adjacent sequences: A091856 A091857 A091858 this_sequence A091860 A091861 A091862
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Mar 13 2004
|
|
EXTENSIONS
|
a(6) onwards by Rick L. Shepherd (rshepherd2(AT)hotmail.com), Sep 08 2009
|
|
|
Search completed in 0.002 seconds
|
