A380478 Nonprime numbers k such that A380459(k) has no divisors of form p^p.

1, 6, 14, 26, 38, 62, 74, 86, 122, 134, 146, 158, 186, 194, 206, 218, 254, 278, 302, 314, 326, 362, 386, 398, 422, 434, 446, 458, 482, 542, 554, 566, 614, 626, 662, 674, 698, 734, 746, 758, 794, 818, 842, 854, 866, 878, 906, 914, 926, 974, 998, 1046, 1082, 1094, 1142, 1154, 1202, 1214, 1226, 1238, 1262, 1266, 1286

Offset: 1

Author

Antti Karttunen, Feb 03 2025

Keywords

• nonn

Comments

See A380468 to find why each term must be squarefree.

After the initial 1 all terms here are even (thus in A039956) because as A276086(k) flips the parity of k, having more than one odd prime factor in k without a single 2 would make A380459(k) a multiple of 4, and thus outside of A048103.

For a similar reason, any term that is not a multiple of 3 may have at most 3 prime factors.

Links

• Antti Karttunen, Table of n, a(n) for n = 1..20000
• Index entries for sequences related to primorial base.

Crossrefs

Cf. A048103, A276086, A380459, A380474 (subsequence), A380477 (characteristic function).

Intersection of A380468 and A018252. (A380468 without primes).

Subsequence of A000469. Subsequence of A039956 (after the initial 1).

Programs

PARI

is_A380478 = A380477;