30122

Appears in sequences

• Tribonacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) with a(0)=0, a(1)=1, a(2)=0.at n=20A001590
• Taylor series related to one in Ramanujan's Lost Notebook.at n=30A006305
• Numbers k such that the continued fraction for sqrt(k) has period 79.at n=22A020418
• Consider the sequence of 4-tuples {0,a,b,c} (c>=a+b; a,b,c>0) which have the smallest integer 'c' required to reach {k,k,k,k} in n steps under map {r,s,t,u}->{|r-s|,|s-t|,|t-u|,|u-r|}. This sequence gives the second term 'a' of these quadruples.at n=31A034803
• Consider the sequence of 4-tuples {0,a,b,c} (c>=a+b; a,b,c>0) which have the smallest integer 'c' required to reach {k,k,k,k} in n steps under map {r,s,t,u}->{|r-s|,|s-t|,|t-u|,|u-r|}. This sequence gives the third term 'b' of these quadruples.at n=29A034804
• a(n) = Sum_{k=0..n} T(n, k), array T as in A047080.at n=17A047081
• Number of partitions of n-set with 2 block sizes.at n=7A088142
• Expansion of -x^2*(x^9-x^8+2*x^7-x^6+x^5-2*x^4+x^2+1) / ((x^6-x^4+x^2+1) * (x^6+x^4+x^2-1)).at n=41A114952
• Triangular array read by rows: T(n,k) is the number of set partitions of {1,2,...,n} that have exactly k distinct block sizes.at n=21A208437
• Tribonacci sequences A000073 and A001590 interleaved.at n=35A213816
• Number of nX6 arrays of the minimum value of corresponding elements and their horizontal, vertical, diagonal or antidiagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and columns, 0..1 nX6 array.at n=7A219352
• Define a sequence of real numbers by b(1)=2, b(n+1) = b(n) + log_2(b(n)); a(n) = smallest i such that b(i) >= 2^n.at n=18A229168
• Number of n X 2 0..3 arrays x(i,j) with each element horizontally or vertically next to at least one element with value (x(i,j)+1) mod 4, no adjacent elements equal, and upper left element zero.at n=9A231057
• "Inside numbers". Pick a term "t" and one of its digits "d". Now jump to the right over d digits if "d" is odd, and to the left over d digits if "d" is even. Whatever the "d" you choose, you will stay on "t".at n=28A284515
• Numbers of the form t_n or t_n + t_{n+1} where {t_n} are the tribonacci numbers A000073.at n=33A308189