19890

Appears in sequences

• Molien series of 4-dimensional representation of u.g.g.r. #8.at n=35A013978
• a(n) = smallest number > a(n-1) such that a(1)*a(2)*...*a(n) + 1 and a(1)*a(2)*...*a(n) - 1 are primes.at n=41A051956
• Composite numbers k such that the difference between the odd and even aliquot parts of k divides k.at n=24A066193
• Numbers k such that phi(k) = 2*tau(k)^2.at n=26A068564
• Averages of twin primes such that the sum of the lower, average and upper parts of the twin primes are averages of other twin primes.at n=11A132929
• a(n) is smallest number with divisors which are congruent to 1, 2, ..., n-1 mod n.at n=25A140539
• Averages of twin primes of the form : i^2+j^2, as sum of two squares.at n=34A143793
• 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), (-1, 1, 0), (0, 1, -1), (1, 0, 1)}.at n=9A148935
• Averages of twin prime pairs of the form : sum of two or more consecutive squares.at n=15A174716
• O.g.f.: exp( Sum_{n>=1} (sigma(2*n^2)-sigma(n^2)) * x^n/n ).at n=12A195584
• G.f.: 1 = Sum_{n>=0} a(n)*x^n/(1 + (n+1)*x)^(2*n+1).at n=5A210096
• Greater of friendly pairs where both terms belong to A014574.at n=2A216058
• Numbers m with m - 1, m + 1 and q(m) - 1 all prime, where q(.) is the strict partition function (A000009).at n=10A235346
• Number of (n+2)X(n+2) 0..1 arrays with every 3X3 subblock sum of the two maximums of the central row and central column plus the two minimums of the diagonal and antidiagonal nondecreasing horizontally and vertically.at n=1A254914
• Number of (n+2)X(2+2) 0..1 arrays with every 3X3 subblock sum of the two maximums of the central row and central column plus the two minimums of the diagonal and antidiagonal nondecreasing horizontally and vertically.at n=1A254916
• T(n,k)=Number of (n+2)X(k+2) 0..1 arrays with every 3X3 subblock sum of the two maximums of the central row and central column plus the two minimums of the diagonal and antidiagonal nondecreasing horizontally and vertically.at n=4A254922
• Numbers n such that for some m, A166133(m)=n, A166133(m+1)=n^2-1, in order of increasing m.at n=31A256406
• Numbers n such that for some m, A166133(m)=n, A166133(m+1)=n^2-1, in increasing order.at n=33A256407
• Numbers n such that n is both the average of some twin prime pair p, q (q = p+2) (i.e., n = p+1 = q-1) and is also the arithmetic mean of the four numbers consisting of the two primes before p and the two primes after q.at n=32A256620
• Numbers n such that n-23, n-1, n+1 and n+23 are consecutive primes.at n=0A263298