21113

Appears in sequences

• Prefix primes in base 8 (written in base 8).at n=44A024768
• T(2n-1,n-2), T given by A026681.at n=6A026686
• Denominators of continued fraction convergents to sqrt(195).at n=6A041363
• Row sums of the triangle in A122820.at n=42A077388
• a(n) = Bell(n) - Fibonacci(n).at n=9A100389
• Numbers n such that there exists at least one number j and pi(m) = d_1 d_2 ... d_j*d_(j+1) d_(j+2) ... d_k where d_1 d_2 ...d_k is the decimal expansion of n.at n=24A112012
• Indices n such that the 3 X 3 matrix with components (row by row) prime(n+k), 0 <= k <= 8, has zero determinant.at n=29A117345
• a(n) = n^3 - n^2 - 2*n + 1.at n=28A123972
• Smallest sum of n consecutive odd primes which is a multiple of n.at n=42A132810
• Expansion of (1 - x)/(1 - 28*x + x^2).at n=3A159668
• Antidiagonal sums of A163280.at n=31A163983
• Sequence defined by the recurrence formula a(n+1)=sum(a(p)*a(n-p)+k,p=0..n)+l for n>=1, with here a(0)=1, a(1)=5, k=-1 and l=1.at n=7A176967
• Composite numbers whose product of digits is 6.at n=30A201055
• E.g.f A(x) satisfies A(x) = 1 + sinh(x)*A(sinh(x)).at n=7A201197
• Numbers that eventually reach 1 under "x -> sum of 4th power of digits of x".at n=17A219111
• Number of partitions p of n such that (maximal multiplicity over the parts of p) = number of 1s in p.at n=40A241131
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 382", based on the 5-celled von Neumann neighborhood.at n=36A271541
• Numbers of the form HMMSS with primes H < 24 and MM, SS < 60, for which the number of seconds after midnight, 3600*H+60*MM+SS, is also prime.at n=21A295011
• a(n) is the smallest number m such that tau(m - 1) = tau(m + 1) = tau(m) + n or 0 if no such m exists, where tau(k) = A000005(k).at n=28A350934
• Square array of distinct positive integers A(n, k), n, k > 0, read and filled the greedy way by antidiagonals upwards such that the concatenations of the terms of two distinct rows are always equal.at n=38A363931