158203

Appears in sequences

• Lexicographically earliest sequence of pairwise coprime triangular numbers.at n=25A034792
• (Nearest integer to n^6/36) / 2.at n=14A061005
• Triangular numbers whose reverse is prime.at n=29A066751
• Triangular numbers which are the product of two primes.at n=32A068443
• Triangular numbers that are also brilliant (A078972).at n=25A113940
• Semiprimes in A006987(n), or semiprime binomial coefficients: C(n,k), 2 <= k <= n-2.at n=33A124000
• Product p*q of two primes with q = 2*p + 1.at n=18A156592
• Numbers n such that A229964(n) = 1.at n=21A229965
• Squarefree numbers (from A005117) with prime divisors in a 2p+1 progression.at n=24A231966
• Triangular numbers which have one or more occurrences of exactly six different digits.at n=16A241789
• Numbers n with the property that the symmetric representation of sigma(n) has four parts, each of width one and two regions meet at the center of the Dyck path.at n=30A264104
• a(n) = A000217(A000217(n)+1).at n=33A267707