19781

Appears in sequences

• a(n) = n-th prime number * n-th lucky number.at n=31A032601
• n-th 6k+1 prime times n-th 6k-1 prime.at n=15A048629
• Non-palindromic numbers such that the two largest proper divisors are palindromes having at least two digits and no other divisor is a palindrome with at least two digits.at n=18A074889
• a(n) = smallest multiple of prime(n) such that a(n) +1 is a multiple of prime(n+1).at n=35A077338
• Let k be an integer consisting of m digits. Then k is a Pithy number if the k-th m-tuple in the decimal digits of Pi is k.at n=2A109514
• Composite numbers generated by the Euler polynomial x^2 + x + 41.at n=26A145292
• Semiprimes which are the sum of three distinct positive cubes in two or more distinct ways.at n=30A180089
• Smallest k>0 such that (5^n-k)*5^n-1 and (5^n-k)*5^n+1 are a twin prime pair or 0 if no such k exists.at n=46A212488
• Total number of parts of multiplicity 10 in all partitions of n.at n=45A222710
• Semiprimes generated by the Euler polynomial x^2 + x + 41.at n=26A228183
• Semiprimes whose prime factors are of equal binary length and which differ from each other in exactly two bit positions.at n=43A261074
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 502", based on the 5-celled von Neumann neighborhood.at n=34A272579
• Number of integers in n-th generation of tree T(1/2) defined in Comments.at n=27A274142
• a(n) = 2*A090495(n) - 1.at n=37A274297
• Decimal representation of the diagonal from the corner to the origin of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 358", based on the 5-celled von Neumann neighborhood.at n=38A287784
• Decimal representation of the diagonal from the corner to the origin of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 358", based on the 5-celled von Neumann neighborhood.at n=39A287784
• p-INVERT of the nonnegative integers (A000027), where p(S) = 1 - S - S^2.at n=13A290990
• Number of nX4 0..1 arrays with every element unequal to 0, 1, 3, 4 or 8 king-move adjacent elements, with upper left element zero.at n=11A305248
• a(n) = 25*n^2/2 - 11*n/2 + 1.at n=40A383465