21135

Appears in sequences

• Numbers k such that k divides the sum of the digits of k^(2k).at n=21A108859
• Terms in A112039 that are divisible by 3, divided by 3.at n=33A112040
• Numbers n with property that for each single digit d of n, we can also see the decimal expansion of the d-th prime as a substring of n. Also n may not contain any zero digits.at n=6A135015
• Number of disconnected simple graphs on n vertices with each component regular.at n=12A165648
• Number of subsets of {1,2,...,n} whose sum is semiprime (cf. A001358, A064911).at n=15A181522
• Potential magic constants of 9 X 9 magic squares composed of consecutive primes.at n=36A191679
• Number of (n+2) X (5+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 0 3 5 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 0 3 5 6 or 7.at n=14A252381
• Anagraprod Integers. Integers N that reproduce their multiset of digits when all the products of two successive digits of N are done (and considered together).at n=54A296451
• T(n, k) = (1/n) * Sum_{d|n} phi(d) * A241171(n/d, k) for n >= 1, T(0, k) = 0^k. Triangle read by rows for 0 <= k <= n.at n=24A327027