login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

A178773
Least palindrome which is the product of n consecutive primes.
0
1, 2, 6, 1001, 5005, 323323
OFFSET
0,2
COMMENTS
A proper subset of A169829.
The next term must exceed the product of 6 primes whose prime index is at least 125000000.
FORMULA
a(3) = 1001 = 7*11*13,
a(4) = 5005 = 5*7*11*13,
a(5) = 323323 = 7*11*13*17*19.
MATHEMATICA
fQ[k_, n_] := Block[{j = Fold[ Times, 1, Prime[Range[k, k + n]]]}, j == FromDigits@ Reverse@ IntegerDigits@ j]; lst = {}; Do[k = 1; While[ ! fQ[k, n], k++ ]; Print[{n + 1, Fold[Times, 1, Prime[Range[k, k + n]]]}], {n, -1, 4}]
CROSSREFS
Sequence in context: A047690 A113569 A252739 * A046857 A129454 A317251
KEYWORD
base,nonn
AUTHOR
Robert G. Wilson v, Jun 11 2010
STATUS
approved