87990

Appears in sequences

• a(n) = [ a(n-1)/a(1) + a(n-3)/a(3) + a(n-5)/a(5) + ... ], for n >= 3.at n=45A022871
• Even triangular numbers with prime indices.at n=40A034955
• a(n) = n^4 - (n-1)^4 + (n-2)^4 - ... 0^4.at n=20A062392
• a(1) = 0, then smallest triangular number such that a(n+1)- a(n) is a palindrome.at n=29A075057
• a(n) = m*(m+1)/2, where m = floor(n^(3/2)).at n=55A185541
• Number of 4Xn 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 0 0 vertically.at n=8A207501
• Sixth derivative of f_n at x=1, where f_n is the n-th of all functions that are representable as x^x^...^x with m>=1 x's and parentheses inserted in all possible ways.at n=17A215836
• Triangle T(n,k) in which n-th row lists the values of the n-th derivative at x=1 of all functions that are representable as x^x^...^x with n x's and parentheses inserted in all possible ways; n>=1, 1<=k<=A000081(n).at n=17A216349
• Triangle T(n,k) in which n-th row lists in increasing order the values of the n-th derivative at x=1 of all functions that are representable as x^x^...^x with n x's and parentheses inserted in all possible ways; n>=1, 1<=k<=A000081(n).at n=36A216350
• n-th derivative of x^(x^(n-1)) at x=1.at n=6A216351
• Triangular arithmetic on half-squares: b(n)*(b(n) - 1)/2 where b(n) = floor(n^2/2).at n=29A227970
• The first of three consecutive triangular numbers the sum of which is equal to the sum of three consecutive primes.at n=31A298168
• Triangular numbers which are products of five distinct primes.at n=23A357590