OFFSET
1,1
EXAMPLE
Let k(n) = n-th composite (A002808(n)). Then:
a(4)=5 because k(4) = 9 = 3^2 and 5=3+2;
a(9)=6 because k(9) = 16 = 2^4 and 6=2+4;
a(10)=7 because k(10) = 18 = 2*3^2 and 7=2+3+2.
MAPLE
A141276 := proc(n) local a, ifs, p, c ; if not isprime(n) then a := 0 ; ifs := ifactors(n)[2] ; for p in ifs do a := a + op(1, p) ; if op(2, p) > 1 then a := a+ op(2, p) ; fi; od: printf("%d, ", a) ; end if; return ; end: for n from 4 to 200 do A141276(n); end do; # R. J. Mathar, Apr 28 2010
CROSSREFS
KEYWORD
nonn
AUTHOR
Juri-Stepan Gerasimov, Aug 08 2008
EXTENSIONS
Entries checked by R. J. Mathar, Apr 28 2010
Edited (with clearer definition) by N. J. A. Sloane, Jun 15 2021
STATUS
approved