|
Search: id:A117877
|
|
| |
|
| 2, 5, 11, 17, 67, 101, 109, 107, 227, 569, 499, 821, 1163, 2153, 1489, 1487, 1579, 4111, 6841, 10739, 5783, 21383, 4729, 3467, 34183, 58741, 19319, 22283, 22279, 22277, 16069, 16067, 17333, 91583, 20479, 20477, 82223, 158363, 31189, 70877, 45061
(list; graph; listen)
|
|
|
OFFSET
|
0,1
|
|
|
FORMULA
|
First occurrence of n in A118123 by primes. A118123 : The number of k's such that prime(n+1) = prime(n) + (prime(n) mod k).
|
|
EXAMPLE
|
a(0)=2 because no k exists and it is the least of the three {2, 3 & 7} in A117563 or A117078.
a(1)=5 because 5 + 5 (mod 3) = 7,
a(2)=11 because 11 + 11 (mod 3) = 11 + 11 (mod 9) = 13.
a(3)=17 because 17 + 17 (mod 3) = 17 + 17 (mod 5) = 17 + 17 (mod 15) = 19,
a(4)=67 because 67 + 67 (mod 7) = 67 + 67 (mod 9) = 67 + 67 (mod 21) = 67 + 67 (mod 63) = 71,
a(5)=101 because 101 + 101 (mod 3) = 101 + 101 (mod 9) = 101 + 101 (mod 11) = 101 + 101 (mod 33) = 101 + 101 (mod 99), etc.
|
|
PROGRAM
|
(PARI) f[n_] := Block[{p = Prime@n, np = Prime[n + 1]}, Length@ Select[ Divisors[2p - np], # >= np - p &]]; t = Table[0, {50}]; Do[ a = f@n; If[a < 50 && t[[a + 1]] == 0, t[[a + 1]] = n; Print[{a, n, Prime@n}]], {n, 100000}]
|
|
CROSSREFS
|
Cf. A118123, A117078, A117563.
Sequence in context: A091936 A038977 A141778 this_sequence A025200 A132455 A132459
Adjacent sequences: A117874 A117875 A117876 this_sequence A117878 A117879 A117880
|
|
KEYWORD
|
nonn,uned
|
|
AUTHOR
|
Remi Eismann and Robert G. Wilson v (rgwv(AT)rgwv.com), May 14 2006
|
|
|
Search completed in 0.002 seconds
|
