|
|
A071393
|
|
Reverse of largest prime factor of n = smallest prime factor of n+1; a(1)=1.
|
|
1
|
|
|
1, 558, 1456, 2170, 2976, 4680, 5328, 6816, 7098, 7812, 9796, 10230, 13192, 13578, 14058, 14260, 15066, 19096, 22320, 26128, 26350, 28542, 28768, 30600, 32338, 33696, 36828, 38440, 40612, 40950, 50268, 53946, 57510, 58590, 62196, 64750
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
EXAMPLE
|
13578 is here since 13578 = 2.3.31.'73' and 13579 = '37'.367.
|
|
MAPLE
|
revdigs:= proc(n) option remember; local L, i;
L:= convert(n, base, 10);
add(L[-i]*10^(i-1), i=1..nops(L));
end proc:
filter:= proc(n) local p;
p:= revdigs(max(numtheory:-factorset(n)));
isprime(p) and p = min(numtheory:-factorset(n+1))
end proc:
filter(1):= true:
|
|
MATHEMATICA
|
Join[{1}, Select[Range[65000], IntegerReverse[FactorInteger[#][[-1, 1]]] == FactorInteger[ #+1][[1, 1]]&]] (* Harvey P. Dale, Mar 29 2018 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|