OFFSET
1,1
MAPLE
A020639 := proc(n) if n = 1 then 1 ; else numtheory[factorset](n) ; min(op(%)) ; end if; end proc:
A177941 := proc(n) option remember; if n = 1 then 5 else A020639((procname(n-1))^2-4) ; procname(n-1)+%-1 ; end if; end proc: seq(A177941(n), n=1..120) ; # R. J. Mathar, Jun 30 2010
MATHEMATICA
NestList[# + FactorInteger[#^2 - 4][[1, 1]] - 1 &, 5, 52] (* or *)
a[1] = 5; a[n_] := a[n] = # + FactorInteger[#^2 - 4][[1, 1]] - 1 &@ a[n - 1]; Array[a, {53}] (* Michael De Vlieger, Feb 07 2016 *)
PROG
(PARI) lista(nn) = {my(va = vector(nn)); va[1] = 5; for (n=2, nn, va[n] = va[n-1] + factor(va[n-1]^2-4)[1, 1] - 1; ); va; } \\ Michel Marcus, Dec 14 2018
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Shevelev, May 15 2010
EXTENSIONS
Entries checked by R. J. Mathar, Jun 30 2010
STATUS
approved