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A217002
Lucas-Carmichael numbers with 6 prime factors.
11
139501439, 196377335, 206238815, 239875559, 287432495, 336545495, 353107799, 381626399, 394426655, 406335215, 461829599, 464972255, 577901519, 592557119, 649351295, 653067359, 674628479, 761212655, 775931519, 777724415, 929892095, 993625919, 1073352959
OFFSET
1,1
LINKS
Daniel Suteu, Table of n, a(n) for n = 1..9382 (first 1000 terms from Donovan Johnson)
EXAMPLE
A006972(385) = 139501439 = 7*11*17*19*71*79.
PROG
(PARI) upto(n, k=6) = my(A=vecprod(primes(k+1))\2, 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))), forprime(q = p, sqrtnint(B\m, k), 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, Sep 03 2022
CROSSREFS
Cf. A006972 (Lucas-Carmichael numbers), A216925, A216926, A216927, A217003, A217091.
Sequence in context: A251505 A034642 A109093 * A036744 A257643 A262532
KEYWORD
nonn
AUTHOR
Donovan Johnson, Sep 22 2012
STATUS
approved