OFFSET
1,1
COMMENTS
a(n) is the largest prime factor of either n or n+3; hence a(p) = p for all prime numbers other than 2.
LINKS
Metin Sariyar, Table of n, a(n) for n = 1..16000
FORMULA
a(p-3) = p for all primes p > 3. - M. F. Hasler, Nov 10 2019
EXAMPLE
For n = 8, n + T(n) = 8 + 36 = 44. The largest prime factor of 44 is 11, so a(8) = 11.
MAPLE
L:=map(max @ numtheory:-factorset, [$1..103]):
zip(max, L[1..-3], L[4..-1]); # Robert Israel, Nov 13 2019
MATHEMATICA
Table[FactorInteger[n+n*(n+1)/2][[-1, 1]], {n, 66}] (* Metin Sariyar, Oct 28 2019 *)
PROG
(PARI) a(n)=A006530(n*(n+3)/2) \\ M. F. Hasler, Nov 10 2019
(Magma) [Max(PrimeDivisors(n*(n+3) div 2)): n in [1..70]]; // Marius A. Burtea, Nov 13 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Ali Sada, Oct 28 2019
EXTENSIONS
Edited by M. F. Hasler, Nov 10 2019
STATUS
approved