1747200domain: NAppears in sequencesa(n) = A002952(n) + A002953(n).at n=18A180277Exponential Riordan array (1,4*x+6*x^2+4*x^3+x^4).at n=24A187084Numbers k for which the repeating part with leading 0's of 1/k in decimal is a palindrome and longer than one digit.at n=14A382638