A217002 Lucas-Carmichael numbers with 6 prime factors.

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

Author

Donovan Johnson, Sep 22 2012

Keywords

• nonn

Examples

			A006972(385) = 139501439 = 7*11*17*19*71*79.
		

Links

• Daniel Suteu, Table of n, a(n) for n = 1..9382 (first 1000 terms from Donovan Johnson)

Crossrefs

Cf. A006972 (Lucas-Carmichael numbers), A216925, A216926, A216927, A217003, A217091.

Programs

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