|
Search: id:A134037
|
|
|
| A134037 |
|
Concatenated first and last digits of Mersenne prime reversals. |
|
+0
3
|
|
| 33, 77, 13, 71, 18, 11, 75, 72, 12, 16, 71, 71, 16, 75, 71, 71, 14, 12, 11, 72
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Not all reversals of Mersenne primes are primes. Concatenation is a convenient way to see whether the prime reversal might be prime (obviously not if ending in an even number or 5).
|
|
FORMULA
|
Generate the Mersenne prime sequence. Reverse the primes. Find the value of the first and last digits and concatenate.
|
|
EXAMPLE
|
a(4)=71 because the first and last digits of the 4th Mersenne prime 127 are 1 and 7. Reversed they are 7 and 1, and concatenated for convenience, 71.
|
|
CROSSREFS
|
Cf. A134038 A134039.
Sequence in context: A063868 A049012 A137187 this_sequence A138841 A138863 A138866
Adjacent sequences: A134034 A134035 A134036 this_sequence A134038 A134039 A134040
|
|
KEYWORD
|
base,more,nonn
|
|
AUTHOR
|
Enoch Haga (Enokh(AT)comcast.net), Oct 02 2007
|
|
|
Search completed in 0.002 seconds
|
