A075572 Smallest prime divisor of sum of three successive terms pertaining to A075571.

3, 5, 3, 7, 5, 3, 3, 5, 7, 3, 11, 11, 3, 3, 7, 5, 5, 5, 11, 13, 5, 11, 17, 3, 5, 13, 3, 3, 7, 5, 13, 5, 5, 7, 3, 13, 7, 3, 13, 5, 5, 7, 19, 7, 7, 23, 3, 5, 5, 23, 17, 7, 3, 3, 11, 19, 3, 29, 13, 29, 7, 7, 13, 3, 5, 5, 3, 5, 5, 13, 7, 5, 5, 5, 7, 5, 17, 17, 3, 31, 19, 3, 5, 11, 19, 37

Offset

0,1

Links

Robert Israel, Table of n, a(n) for n = 0..10000

Maple

P:= select(isprime, [seq(i, i=7..1000, 2)]): nP:= nops(P):
R:= 3, 5: s:= 8: A:= NULL;
for i from 0 to 100 do
  found:= false;
  for j from 1 to nP do
    if not isprime(s+P[j]) then
      found:= true; A:= A, min(numtheory:-factorset(s+P[j])); R:= R, P[j]; s:= R[-2]+P[j]; P:= subsop(j=NULL, P); nP:= nP-1; break
    fi;
  od;
  if not found then break fi;
od:
A; # Robert Israel, Jun 06 2025

Prog

(PARI) pr=vector(10000):v=vector(100):v[1]=3:v[2]=5:pr[3]=1:pr[5]=1:for(n=3, 100, forprime(p=3, 10000, if(!pr[p]&&!isprime(v[n-2]+v[n-1]+p), print1(factor(v[n-2]+v[n-1]+p)[1, 1]", "):v[n]=p:pr[p]=1:break)))

Crossrefs

Cf. A075571.

Sequence in context: A095366 A029604 A079602 * A089992 A074593 A144294

Adjacent sequences: A075569 A075570 A075571 * A075573 A075574 A075575

Keyword

nonn

Author

Amarnath Murthy, Sep 25 2002

Extensions

Corrected and extended by Ralf Stephan, Mar 27 2003

Status

approved