61425

Appears in sequences

• Second diagonal of A027517.at n=10A027523
• Tritriangular numbers: a(n) = binomial(binomial(n,2),2) = n*(n+1)*(n-1)*(n-2)/8.at n=27A050534
• Consider 2n tennis players; a(n) is the number of matches needed to let every possible pair play each other.at n=12A062346
• Triangular numbers which are products of triangular numbers larger than 1.at n=35A068143
• Triangular numbers which are 7-almost primes.at n=21A076581
• a(n) = smallest number which can be expressed as sum of d consecutive positive integers in exactly n ways (where d>0 is a divisor of the number).at n=26A082637
• Numbers n which when converted to base 4, reversed and converted back to base 10 yield a number m such that n mod m = 0. Cases which are trivial or result in digit loss are excluded.at n=5A091078
• a(1) = 1, a(2) = 2, next terms up to a(2n-1) are obtained by multiplying previous terms a(n-1) by n+1, a(n-2) by n+2 etc. a(2) by (2n-2) and a(1) by 2n-1. On similar lines a(2n) = 2n*a(2n-2), a(2n+1) = (2n+1)*a(2n-1) and so on.at n=44A109844
• Triangular numbers which are the sum of distinct double factorials (A006882).at n=31A115650
• Smallest term in the Hofstadter sequence A005243 having exactly n representations as sum of consecutive earlier terms.at n=17A118166
• Dimensions of the irreducible representations of the simple Lie algebra of type E6 over the complex numbers, listed in increasing order.at n=20A121737
• a(n) = AlexanderPolynomial[n] defined as Det[Transpose[S]-n S] where S is Kronecker Product of two 2 X 2 Seifert matrices {{-1, 1}, {0, -1}} [X] {{-1, 1}, {0, -1}} = {{1, -1, -1, 1}, {0, 1, 0, -1}, {0, 0, 1, -1}, {0, 0, 0, 1}}.at n=16A138849
• Triangle read by rows, A100861(n,k) * A118930(k).at n=34A152685
• G.f. is the polynomial (1-x^3) * (1-x^6) * (1-x^9) * (1-x^12) * (1-x^15) * (1-x^18) * (1-x^21) * (1-x^24) * (1-x^27) / (1-x)^9.at n=11A162602
• Triangle of Generalized Runyon numbers R_{n,k}^(4) read by rows.at n=25A173621
• a(n) = smaller member of n-th pair of distinct, positive, triangular numbers whose sum and difference are also triangular numbers.at n=12A185129
• a(n) = smaller member of n-th pair of distinct, positive, triangular numbers whose sum and difference are also triangular numbers.at n=16A185129
• Triangular numbers that are the product of two triangular numbers greater than 1.at n=24A188630
• Triangular numbers that are the product of three distinct triangular numbers greater than 1.at n=16A225440
• Number of partitions p of n not including ceiling(mean(p)) as a part.at n=47A241337