42135

Appears in sequences

• Pendulum numbers: alternately append n to beginning or end of previous term.at n=4A053063
• Array read by rows in which the n-th row contains the multiples of n in increasing order using all the digits of first n numbers.at n=34A078189
• The number of disconnected 2k-regular simple graphs on 4k+5 vertices.at n=7A184325
• Alternately concatenate the decimal digits from front to back 1...n such that n is always to the right.at n=4A281253
• Numbers k such that sigma(k) = psi(k) + 2 * tau(k).at n=45A387962