20502

Appears in sequences

• a(n) = smallest number k such that Product_{i=2..k+1} prime(i)/(prime(i)-1) > n.at n=11A005580
• Base-10 palindromes that start with 2.at n=27A043037
• Palindromes that are divisible by 6.at n=30A045641
• Palindromic and divisible by 9.at n=34A045644
• Palindromes with exactly 5 prime factors (counted with multiplicity).at n=26A046331
• First differences are A005563.at n=38A047732
• Palindromic untouchable numbers.at n=21A048187
• a(n) = n(n+7)(n+1)(n^2+2n+12)/120.at n=16A051746
• Row sums of triangle in A059274.at n=6A059276
• Nontrivial palindromes k such that phi(k) is also a palindrome.at n=2A067723
• Numbers n such that phi(reversal(n)) = reversal(phi(n)). Ignore leading 0's.at n=18A069282
• Numbers n such that n and phi(n) are both palindromes.at n=11A069747
• Final terms of rows of A077529.at n=16A077530
• Palindromes divisible by their digit sum.at n=43A082232
• a(n) = n^2 concatenated with reverse(n^2) divided by 11.at n=15A084009
• Sum of A095734(p) for all primes p such that Fib(n+1) <= p < Fib(n+2) (where Fib = A000045).at n=23A095732
• Palindromic abundant numbers.at n=43A098775
• Consider all (2n+1)-digit palindromic primes of the form 70...0M0...07 (so that M is a palindrome with <= 2n-1 digits); a(n) = smallest such M.at n=38A100956
• Antidiagonal sums in A101321.at n=26A101338
• Square table, read by antidiagonals, where T(n,k) equals the number of k-tournament sequences of length n for k>=1, with T(0,k) = 1 for k>=1 and T(n,1) = 0 for n>0.at n=51A113080