37367

Appears in sequences

• Numbers k such that j(k)*phi(k) = sigma(phi(k)), j(k) = A033831(k).at n=18A033856
• T(n,n+3), array T as in A047110.at n=8A047118
• Triangle read by rows: a(n,m) = T[n,m,m] where T[i,j,k] is the 3-dimensional pyramid defined by T[n,m,0]=1 and T[i,j,k]=0 if j>i or k>j and T[i,j,k]=T[i-1,j,k]+T[i,j-1,k]+T[i,j,k-1].at n=33A065078
• In base 3: n sets a new record for the number of Reverse and Add! steps needed to reach a palindrome starting with n.at n=11A077406
• Number of primitive (=aperiodic) 8-ary words with length less than or equal to n which are earlier in lexicographic order than any other word derived by cyclic shifts of the alphabet.at n=5A320092
• a(n) is the least k such that phi(k) + d(k) = 2^n, or -1 if there is no such k, where phi(k) = A000010(k) is Euler's totient function and d(k) = A000005(k) is the number of divisors of k.at n=14A357898
• Expansion of e.g.f. exp(-x) / (1 + x*exp(x)).at n=9A368272
• Pentagonal numbers which are products of three distinct primes.at n=37A381650
• a(1) = 1 and thereafter a(n) = a(n-1) + j(n-1) where j(1) = 1 and then j(n) = j(n-1)-1 if a(n) is composite or j(n) = 2*j(n-1) if a(n) is prime.at n=44A382671