21468

Appears in sequences

• Sum_{1<=k<n} gcd(k!,n!/k!).at n=14A014454
• Number of partitions of n into parts not of the form 23k, 23k+5 or 23k-5. Also number of partitions with at most 4 parts of size 1 and differences between parts at distance 10 are greater than 1.at n=39A035993
• Square array of coefficients of binomial polynomials, read by antidiagonals.at n=42A080959
• Output of the linear congruential pseudo-random number generator used in function rand() as described in Kernighan and Ritchie, when seeded with 0.at n=1A096554
• Irregular square reversible numbers. Numbers which when squared and written backwards give a square again, but don't satisfy reverse(n^2) = reverse(n)^2.at n=20A129914
• Riordan array (1/(1+4x+x^2), x/(1+4x+x^2)).at n=29A159764
• Nearest integer to 1 / Sum_{p prime, 2^n < p <= 2^(n+1)} (Kronecker(-1/p)/p).at n=20A166510
• Pascal-like triangle with trigonometric properties, row sums = powers of 4; generated from shifted columns of triangle A180062.at n=51A180063
• Number of 4-step E, S, NW and NE-moving king's tours on an n X n board summed over all starting positions.at n=20A187587
• Triangle of coefficients of Chebyshev's S(n,x+4) polynomials (exponents of x in increasing order).at n=29A207823
• Triangle T(n,k) of the numbers of nodes in all non-extendable (complete) non-self-adjacent simple paths within a square lattice bounded by rectangles with nodal dimensions n and k, n >= k >= 2.at n=16A214397
• Triangle read by rows: T(n,k) is the number of words over alphabet {0,1,2,3} having exactly k occurrences of the string 01, where n>=0 and k>=0.at n=21A261711
• Sum over all partitions of n of the number of distinct parts i of multiplicity i+1.at n=44A276434
• Integers k such that k^2 is not a palindrome and the square root of the reverse of k^2 yields an integer with the same number of digits as k that is not the reverse of k.at n=5A284986
• G.f.: Sum_{n>=0} (n+1) * x^n * (1 + x^n)^n.at n=60A326002