OFFSET
1,2
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..20000
FORMULA
a(p) = (p+1) for prime p.
Row sums of triangle A143151.
a(n) = Sum_{d|n} A020639(d). - Antti Karttunen, Nov 12 2021
EXAMPLE
MAPLE
read transforms : A020639 := proc(n) local i ; if n = 1 then 1; else for i from 1 do if n mod ithprime(i) = 0 then RETURN(ithprime(i)) ; fi; od: fi; end: a020639 := [seq(A020639(n), n=1..100)] : a143152 := MOBIUSi(a020639) : for i from 1 to nops(a143152) do printf("%d, ", op(i, a143152)) ; od: # R. J. Mathar, Aug 11 2008
PROG
(PARI)
A020639(n) = if(1==n, n, (factor(n)[1, 1]));
CROSSREFS
KEYWORD
nonn
AUTHOR
Gary W. Adamson, Jul 27 2008
EXTENSIONS
Extended beyond a(14) by R. J. Mathar, Aug 11 2008
Name amended by Antti Karttunen, Nov 12 2021
STATUS
approved