55620

Appears in sequences

• Consider sequence of fractions A066657/A066658 produced by ratios of terms in A066720; let m = smallest integer such that all fractions 1/n, 2/n, ..., (n-1)/n have appeared when we reach A066720(m) = k; sequence gives values of k; set a(n) = -1 if some fraction i/n never appears.at n=11A066848
• Floor(1/{(7+n^4)^(1/4)}), where {}=fractional part.at n=45A184631
• Number of nX4 binary arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two not more than once.at n=5A269085
• Number of nX6 binary arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two not more than once.at n=3A269087
• T(n,k)=Number of nXk binary arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two not more than once.at n=39A269089
• T(n,k)=Number of nXk binary arrays with some element plus some horizontally, vertically or antidiagonally adjacent neighbor totalling two not more than once.at n=41A269089
• Exponential (2,4)-perfect numbers: numbers m such that esigma(esigma(m)) = 4m, where esigma(m) is the sum of exponential divisors of m (A051377).at n=26A328133
• Numbers k sandwiched between twin primes, such that k times the reverse of k is also sandwiched between twin primes.at n=34A357076
• Triangle read by rows: T(n,k) is the number of weakly connected simple digraphs on n labeled nodes with k strongly connected components.at n=19A361591
• Triangle read by rows: T(n,k) is the number of labeled weakly graded (ranked) posets with n elements and rank k.at n=24A361951