OFFSET
1,1
REFERENCES
M. Kraitchik, Recherches sur la Théorie des Nombres. Gauthiers-Villars, Paris, Vol. 1, 1924, Vol. 2, 1929, see Vol. 1, p. 53.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 200 terms from Harry J. Smith)
MATHEMATICA
up=10^6; a=1; Sort[Reap[While[ a<up, b=a; While[ b<up, c=b; While[ c<up, If[ PrimeQ[ c+1], Sow[ c+1]]; c *= 5]; b *= 3]; a *= 2]][[2, 1]]] (* Giovanni Resta, Jul 18 2017 *)
PROG
(PARI) { default(primelimit, 16600000); n=0; forprime (p=2, 16600000, m=p-1; p2=p3=p5=0; s=m; r=0; while(r==0, q=s\2; r=s-2*q; s=q; if(r==0, p2++)); s=m; r=0; while(r==0, q=s\3; r=s-3*q; s=q; if(r==0, p3++)); s=m; r=0; while(r==0, q=s\5; r=s-5*q; s=q; if(r==0, p5++)); if (m == 2^p2*3^p3*5^p5, n++; write("b002200.txt", n, " ", p)); if (n >= 200, break); ); } \\ Harry J. Smith, May 25 2009
(PARI) { n=5000; cache=10^5; v=vector(cache); x2=2; x3=3; x5=5; i=j=k=1; v[1]=1; for(m=2, cache, v[m]=t=min(x2, min(x3, x5)); if(x2==t, x2=2*v[i++]); if(x3==t, x3=3*v[j++]); if(x5==t, x5=5*v[k++]); ); i=0; c=0; while(c<n, i++; if(isprime(v[i]+1), c++; print(c" "v[i]+1))); } \\ Jean-Marie Madiot, Jul 17 2017
(Magma) [p: p in PrimesUpTo(5000) | forall{d: d in PrimeDivisors(p-1) | d le 5}]; // Bruno Berselli, Sep 24 2012
(GAP)
K:=10^7;; # to get all terms <= K.
A:=Filtered([1..K], IsPrime);;
B:=List(A, i->Factors(i-1));;
C:=[];; for i in B do if Elements(i)=[2] or Elements(i)=[2, 3] or Elements(i)=[2, 5] or Elements(i)=[2, 3, 5] then Add(C, Position(B, i)); fi; od;
A002200:=Concatenation([2], List(C, i->A[i])); # Muniru A Asiru, Sep 10 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
Better description and more terms from Vladeta Jovovic, May 08 2003
STATUS
approved