125521

Appears in sequences

• Composite numbers whose prime factors contain no digits other than 1 and 4.at n=11A036304
• Odd palindromes which are semiprimes with an even number of digits.at n=25A132288
• Numbers k such that k and k^2 use only the digits 1, 2, 4, 5 and 7.at n=19A136989
• Composite palindromes whose divisors > 1 are all nontrivial palindromes (i.e., palindromes with at least two digits).at n=27A329100
• Expansion of g.f. Sum_{n>=1} q^n/(1-q^n-q^(3*n)).at n=32A368688