A063969 Numbers k such that sopf(k) = sopf(k+3), where sopf(k) = A008472(k).

7, 60, 147, 407, 470, 1053, 1175, 3431, 3822, 5126, 5960, 6280, 6321, 6897, 7200, 8687, 9243, 10760, 12614, 15093, 16153, 18080, 18818, 19668, 20433, 20976, 24648, 26826, 30804, 44016, 45878, 46221, 47423, 55965, 58506, 58682, 59645, 63897

Offset

1,1

Links

Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 1000 terms from Harry J. Smith)

Mathematica

Select[Range[65000], Total[Transpose[FactorInteger[#]][[1]]] == Total[ Transpose[FactorInteger[#+3]][[1]]]&] (* Harvey P. Dale, Jan 19 2013 *)

Prog

(PARI) sopf(n, s, fac, i)=fac=factor(n); for(i=1, matsize(fac)[1], s=s+fac[i, 1]); return(s);
j=[]; for(n=1, 100000, if(sopf(n)==sopf(n+3), j=concat(j, n))); j
(PARI) sopf(n)= { local(f, s=0); f=factor(n); for(i=1, matsize(f)[1], s+=f[i, 1]); return(s) }
{ n=0; for (m=1, 10^9, if(sopf(m)==sopf(m + 3), write("b063969.txt", n++, " ", m); if (n==1000, break)) ) } \\ Harry J. Smith, Sep 04 2009

Crossrefs

Cf. A008472, A006145.

Sequence in context: A183260 A285227 A358132 * A366613 A303120 A015570

Adjacent sequences: A063966 A063967 A063968 * A063970 A063971 A063972

Keyword

nonn

Author

Jason Earls, Sep 05 2001

Status

approved