A073884 a(1)=2. Let S(k) = sum of k terms. If S(n) is prime then a(n+1) is the smallest prime not included earlier else a(n+1) is the smallest composite number not included earlier.

2, 3, 5, 4, 6, 8, 9, 7, 10, 12, 14, 15, 16, 18, 20, 11, 21, 13, 22, 24, 25, 26, 27, 28, 30, 32, 33, 34, 35, 36, 38, 39, 40, 42, 44, 45, 46, 48, 49, 17, 50, 51, 52, 54, 55, 56, 57, 58, 60, 19, 62, 63, 64, 65, 66, 68, 69, 70, 23, 72, 74, 75, 29, 76, 77, 78, 80, 81, 82, 84, 85, 31

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

P, C:= selectremove(isprime, [$2..100]):
np:= nops(P): nc:= nops(C):
ip:= 1: ic:= 0: t:= 2: R:= 2:
do
  if isprime(t) then
    ip:= ip+1;
    if ip > np then break fi;
    R:= R, P[ip];
    t:= t + P[ip];
  else
    ic:= ic+1;
    if ic > nc then break fi;
    R:= R, C[ic];
    t:= t + C[ic];
  fi
od:
R; # Robert Israel, Oct 07 2024

Crossrefs

Sequence in context: A073298 A073291 A073280 * A209293 A328021 A361504

Adjacent sequences: A073881 A073882 A073883 * A073885 A073886 A073887

Keyword

nonn

Author

Amarnath Murthy, Aug 17 2002

Extensions

Corrected and extended by Sean A. Irvine, Nov 29 2009

Offset corrected by Robert Israel, Oct 09 2024

Status

approved