OFFSET
1,1
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..1262
EXAMPLE
The 4th prime, 7, is A109890(23), so a(4) = 23.
MAPLE
A109890 := proc(nmin) local a, i, k, apsum; a := [1] ; apsum := 1 ; while nops(a) < nmin do k := 1; while k in a or not ( apsum mod k = 0 or k mod apsum = 0 ) do k := k+1 ; od ; a := [op(a), k] ; apsum := apsum+k ; od; RETURN(a) ; end: A111240 := proc(nmin) local a, a109890, n, i; a := [] ; a109890 := A109890(nmin) ; n := 1; while member( ithprime(n), a109890, 'i') do a := [op(a), i] ; n := n+1 ; od; RETURN(a) ; end: A111240(560) ; # R. J. Mathar, Aug 20 2007
MATHEMATICA
nn = 1000; c[_] := False; p[_] := 0;
Array[Set[{a[#], c[#]}, {#, True}] &, 2];
r = 0; s = a[1] + a[2]; p[2] = 2;
Monitor[Do[k = SelectFirst[Divisors[s], ! c[#] &];
c[k] = True;
Map[(If[p[#] == 0, Set[p[#], n]]; If[# > r, r = #]) &,
FactorInteger[k][[All, 1]]];
s += k, {n, 3, nn}], n];
s = 1; Reap[While[Set[k, p[Prime[s]]] > 0, Sow[k]; s++] ][[-1, 1]] (* Michael De Vlieger, Apr 26 2024 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Oct 30 2005
EXTENSIONS
More terms from R. J. Mathar, Aug 20 2007
More terms from David Wasserman, Jan 07 2009
STATUS
approved