A354218 Records in A076978, divided by 2.

1, 3, 15, 105, 1155, 1365, 19635, 23205, 636405, 10555545, 24484845, 869107785, 14797252681546335, 92442344345566215, 40334203530676690635, 1451417351374223318085, 6087255082617244520985, 469256253416014832182075245585, 1519012498286389398934397206158552189345

Offset

1,2

Links

Hugo Pfoertner, Table of n, a(n) for n = 1..52.

Mathematica

1/2*Union@ FoldList[Max, Array[Times @@ FactorInteger[Times @@ Range[#1 + 1, #2 - 1]][[All, 1]] & @@ Map[Prime, # + {0, 1}] &, 180, 2]] (* Michael De Vlieger, May 20 2022 *)

Prog

(Python)
from sympy import sieve as p, primefactors
def A076978_halfen(n): # for all integers n > 1
    result = 1
    for composites in range(p[n]+1, p[n+1]):
        for primefactor in primefactors(composites):
            if result % primefactor != 0: result *= primefactor
    return result//2
A354218 = [1]
for n in range(2, 180):
    if  A076978_halfen(n) > A354218[-1]: A354218.append(A076978_halfen(n))
print(A354218) # Karl-Heinz Hofmann, May 20 2022
(PARI) a354218(maxterm) = {my(mp=0, pp=3); forprime(p=5, oo, my(L=List()); for(j=pp+1, p-1, my(f=factor(j), nf=#f~); for(k=1, nf, listput(~L, f~[1, k]))); listsort(L, 1); my(mpp=prod(k=1, #L, L[k])); if(mpp>mp, if(mpp<2*maxterm, print1(mpp/2, ", "); mp=mpp, return)); pp=p)};
a354218(10^75)

Crossrefs

Cf. A007947, A076978, A354217.

Sequence in context: A360438 A000268 A207818 * A118750 A070826 A048599

Adjacent sequences: A354215 A354216 A354217 * A354219 A354220 A354221

Keyword

nonn

Author

Hugo Pfoertner, May 19 2022

Status

approved