20031

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 47.at n=40A031545
• Numerators of continued fraction convergents to sqrt(805).at n=6A042552
• Second differences of sequence A160644.at n=41A160648
• Least natural number n in increasing order such that the sum of decimal digits is equal to A001223(n).at n=39A179462
• Expansion of 1 + Sum_{n>=1} (x^(n^2) / Product_{k>=n} (1 - x^k)).at n=37A188216
• Numbers n such that 9^n + 3^(n+1) - 1 is prime.at n=22A214700
• Number of distinct values of the sum of 4 products of three 0..n integers.at n=17A225261
• Number of ways of writing n as the sum of 9 triangular numbers.at n=18A226253
• Integers n of the form 8k+7 that are sum of distinct squares of the form m, m+1, m+2, m+4, where m == 1 (mod 4).at n=17A243578
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 670", based on the 5-celled von Neumann neighborhood.at n=34A273394
• Numbers k such that (23*10^k - 83)/3 is prime.at n=19A293027
• Least number k such that the determinant of the symmetric Toeplitz matrix formed by its decimal digits is equal to n.at n=42A307887