21775

Appears in sequences

• a(n) is least k such that k and 5k are anagrams in base n (written in base 10).at n=20A023097
• Numbers k such that 100k+1, 100k+3, 100k+7, 100k+9 are all primes.at n=32A064687
• Absolute value of coefficient of x^3 in polynomial whose zeros are 5 consecutive integers starting with the n-th integer.at n=9A127694
• a(n) = n*(n+1)*(8*n + 1)/6.at n=25A132124
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 1, 1), (0, 0, -1), (0, 0, 1), (1, 0, 1)}.at n=8A150338
• a(n) = 15n^2 + 3n + 1.at n=37A165806
• Numbers k such that k^k = k (mod prime(k)).at n=8A177005
• a(n) is the smallest number that is the sum of both 2n-1 and 2n+1 consecutive primes.at n=13A213174
• -5-Knödel numbers.at n=27A225509
• Numbers N such that N = P//Q = R//S, where // is the concatenation function, satisfying the following properties: P and S are m-digit integers, Q and R are k-digit integers, k and m are distinct positive integers, and P*Q = R*S.at n=32A245385
• Numbers in A245385 where P, Q, R, and S are all distinct.at n=13A245386
• Main diagonal of Ludic array A255127 (and A255129): a(n) = A255127(n,n).at n=24A255410
• a(n) = n*(n^3 + 2*n^2 - 5*n + 10)/8.at n=20A294259
• Number of n X 3 0..1 arrays with every element equal to 0, 2 or 3 horizontally or antidiagonally adjacent elements, with upper left element zero.at n=11A301902
• Numbers k such that k and k+1 have the same sum of 5-smooth divisors.at n=14A355713
• Integers without 0 as a digit, with an odd number of digits, that are not repdigits, and such that the 2 products [d_1 d_2...dk]*[d_k+1 d_k+2...d_2k+1] and [d_1 d_2...d_k+1]*[d_k+2 d_k+2...d_2k+1] are equal.at n=6A385145