20010

Appears in sequences

• Base-9 palindromes that start with 3.at n=24A043030
• Numbers whose sum of digits is 3.at n=31A052217
• Smallest multiple of n with digit sum = 3, or 0 if no such number exists, e.g. a(9k)= 0 = a(11k).at n=45A069522
• To get a(n), write n in balanced ternary notation (using only digits -1, 0, 1, -1), then change -1's to 0's, 0's to 1's, and 1's to 2's.at n=44A072998
• Take the list t(n,0) = {1,...,n}; denote by t(n,j) this list after rotating to left (or right) by j positions. Calculate inner product of t(n,0) and t(n,j) and denote the value by s(n,j). Compute this inner product for all j = 1..n and choose the smallest. This is a(n).at n=44A088003
• Binary numbers with 2 replacing 1 in odd positions.at n=18A095914
• Numbers k such that 3 and 5 do not divide binomial(2*k, k).at n=45A129508
• Numbers n that raised to the powers from 1 to k (with k>=1) are multiple of the sum of their digits (n raised to k+1 must not be a multiple). Case k=10.at n=28A135195
• a(1)=1, a(n) = a(n-1) + n^3 if n odd, a(n) = a(n-1) + n^1 if n is even.at n=19A140153
• a(n) is the minimal values of A007947((2^n)*m*(2^n-m)).at n=17A143702
• a(n+1) is the least integer > a(n) containing all digits of a(n); a(1)=2.at n=18A155890
• Number of reduced words of length n in Coxeter group on 5 generators S_i with relations (S_i)^2 = (S_i S_j)^5 = I.at n=7A163316
• Numbers k such that the average digit of k^2 is 1.at n=23A164771
• Sum of any three adjacent digits of n^2 is a square.at n=33A174397
• Numbers n such that sum of squares of factorials of digits of n is a power of 2.at n=48A174570
• Numbers that are 5-digit palindromes in at least two bases.at n=25A180454
• "Early bird" squares: write the square numbers in a string 149162536496481100... . Sequence gives numbers k such that k^2 occurs in the string ahead of its natural place.at n=37A181585
• Cantor's ordering of positive rational numbers, where a(n) is the balanced ternary representation of the "factorization" of the positive rational number into terms of A186285.at n=33A185169
• Values of b such that (c+9b)*prime(n)#-1 is the least prime such that (c+kb)*prime(n)#-1 are all primes for 0 <= k <= 9, or 0 if there is no solution with c+9b < prime(n)#.at n=19A188367
• Numbers such that the sum of the largest and the smallest prime divisor equals the sum of the other distinct prime divisors.at n=29A199745