3498000

Appears in sequences

• a(n) = 4^n - C(4,3)*3^n + C(4,2)*2^n - C(4,1).at n=10A000919
• Number of primitive (aperiodic) words of length n which contain exactly four different symbols.at n=10A056269
• Palindromes using exactly four different symbols.at n=20A056455
• Palindromes using exactly four different symbols.at n=21A056455
• Number of periodic palindromes using exactly four different symbols.at n=20A056490