72171

Appears in sequences

• Numbers of the form 3^i*11^j.at n=31A003597
• Numerators of continued fraction convergents to sqrt(470).at n=6A041896
• Odd numbers divisible by exactly 9 primes (counted with multiplicity).at n=4A046322
• Number of ternary trees (A001764) with n nodes and maximal diameter.at n=9A064017
• Numbers k such that S(k)=d(k), where S(k) is the Kempner function (A002034) and d(k) is the number of divisors of k (A000005).at n=29A073307
• Numbers n such that number of divisors of n divides S(n), the Kempner function A002034.at n=40A073413
• Expansion of g.f. c(3x)^3, where c(x) is the g.f. of A000108.at n=5A101601
• Numbers of the form (9^i)*(11^j), with i, j >= 0.at n=16A108687
• Riordan array (1, x*c(3x)), c(x) the g.f. of A000108.at n=39A110518
• a(n) = 11*3^n.at n=8A120354
• Smallest odd n-almost prime m such that m-2 and m+2 are both prime (cousin primes).at n=8A145031
• Numbers which can be expressed as the product of numbers made of only threes.at n=34A161141
• Numbers which can be expressed as the product of numbers made of only nines.at n=13A161147
• Numbers n such that tau(phi(n)) = sigma(rad(n)).at n=28A173745
• Number of n X 4 0..1 arrays avoiding 0 0 0 and 1 0 1 horizontally and 0 0 1 and 1 0 1 vertically.at n=19A207165
• Numbers k such that the last 9 digits of the k-th Lucas number are 1-9 pandigital.at n=21A216488
• a(n) = 3^n*A123335(n). Rational parts of the integers in Q(sqrt(2)) giving the length of a Lévy C-curve variant at iteration step n.at n=6A251732
• Fixed points of A300956.at n=9A300958
• Let S = smallest missing positive number, adjoin S, 3*S, 9*S, 27*S, 81*S, ... to the sequence until reaching a term that has S as a substring; reset S to the smallest missing positive number, repeat.at n=40A331631
• Numbers k with property that k is the least logarithmically smooth numbers (meaning largest prime factor of k is less than log(k)) having squarefree kernel equal to squarefree kernel of k.at n=28A333961