|
Search: id:A122467
|
|
|
| A122467 |
|
Write n-th semiprime in binary, sum as if decimal numbers. |
|
+0
3
|
|
| 100, 210, 1211, 2221, 3331, 4442, 14543, 24653, 35654, 46664, 146665, 246675, 346686, 446796, 546907, 648017, 758018, 868029, 978140, 1089141, 1200151, 1311261, 2311262, 3311363, 4312373, 5313474, 6323484, 7333585, 8343695
(list; graph; listen)
|
|
|
OFFSET
|
1,1
|
|
|
COMMENT
|
Partial sum of A122466. Write n-th semiprime in binary, sum as if decimal numbers. Primes in this sequence begin a(4) = 2221, a(5) = 3331, a(7) = 14543, and a(34) = 13398139.
|
|
FORMULA
|
a(n) = SUM[i=1..n]A122466(i) = SUM[i=1..n]A007088(A001358(i)).
|
|
EXAMPLE
|
a(4) = 100 + 110 + 1001 + 1010 = 2221 because the first 4 semiprimes can be written in binary as 100_2 + 110_2 + 1001_2 + 1010_2.
a(34) = 100 + 110 + 1001 + 1010 + 1110 + 1111 + 10101 + 10110 + 11001 + 11010 + 100001 + 100010 + 100011 + 100110 + 100111 + 101110 + 110001 + 110011 + 110111 + 111001 + 111010 + 111110 + 1000001 + 1000101 + 1001010 + 1001101 + 1010010 + 1010101 + 1010110 + 1010111 + 1011011 + 1011101 + 1011110 + 1011111 = 13398139 is prime.
|
|
CROSSREFS
|
Cf. A000040, A001358, A007088, A004676, A122466.
Sequence in context: A044713 A031498 A053402 this_sequence A027604 A116145 A104908
Adjacent sequences: A122464 A122465 A122466 this_sequence A122468 A122469 A122470
|
|
KEYWORD
|
base,easy,nonn
|
|
AUTHOR
|
Jonathan Vos Post (jvospost2(AT)yahoo.com), Sep 09 2006
|
|
|
Search completed in 0.002 seconds
|
