A217091 Lucas-Carmichael numbers with 8 prime factors.

199195047359, 220323712895, 259305479279, 325451502935, 472765412735, 491091874559, 498357905759, 517270926095, 609349053599, 769658803199, 832015353455, 853833772799, 898951575599, 962940227039, 1087044101759, 1122857491679, 1249765950719, 1297923596255

Offset

1,1

Links

Daniel Suteu and Donovan Johnson, Table of n, a(n) for n = 1..5323 (terms 1..1000 from Donovan Johnson)

Example

A006972(5453) = 199195047359 = 7*11*17*19*23*31*47*239.

Prog

(PARI) upto(n, k=8) = my(A = vecprod(primes(k)), B=n); (f(m, l, p, k, u=0, v=0) = my(list=List()); if(k==1, forprime(p=u, v, my(t=m*p); if((t+1)%l == 0 && (t+1)%(p+1) == 0, listput(list, t))), my(s = sqrtnint(B\m, k)); forprime(q = p, s, my(t = m*q); my(L=lcm(l, q+1)); if(gcd(L, t) == 1, my(u=ceil(A/t), v=B\t); if(u <= v, my(r=nextprime(q+1)); if(k==2 && r>u, u=r); list=concat(list, f(t, L, r, k-1, u, v)))))); list); vecsort(Vec(f(1, 1, 3, k))); \\ Daniel Suteu, Aug 29 2022

Crossrefs

Cf. A006972 (Lucas-Carmichael numbers), A216925, A216926, A216927, A217002, A217003.

Sequence in context: A288262 A233624 A104800 * A144173 A127343 A108048

Adjacent sequences: A217088 A217089 A217090 * A217092 A217093 A217094

Keyword

nonn

Author

Donovan Johnson, Sep 26 2012

Status

approved