20033

Appears in sequences

• a(n) = Sum_{k=1..n} k*phi(k).at n=45A011755
• a(n) = A077698(n+1)/A077698(n).at n=16A077699
• If p(k) is the k-th prime, then the n-th set of 3 consecutive cousin prime pairs starts at p(a(n)).at n=29A095970
• If p(k) is the k-th prime, then the n-th set of 4 consecutive cousin prime pairs starts at p(a(n)).at n=6A095971
• a(n) = (1/6)*(n+1)*(10*n^2 + 17*n + 12).at n=22A102296
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (0, 0, 1), (0, 1, 0), (1, 0, 1), (1, 1, -1)}.at n=7A151133
• 1/4 the number of n X n arrays of squares of integers with every 2X2 subblock summing to 25.at n=10A159225
• A027642(6*n+6)/(sequence of period 2:repeat 42,210).at n=21A216639
• Number of partitions of n such that (maximal multiplicity of parts) > (multiplicity of the maximal part).at n=37A240302
• Let f(p,i) = smallest prime m >= p such that m == i (mod p); a(n) = Sum_{i=0..p-1} f(p,i), where p = n-th prime.at n=18A243076
• Odd squarefree numbers n > 1 such that lambda(n)^2 = phi(n), where lambda is the Carmichael lambda function and phi is Euler's totient function.at n=20A276980
• Maximally idempotent integers with three or more factors.at n=32A306812
• a(n) = Sum_{i=1..n, gcd(i,n)=1} i*phi(i) where phi is Euler's totient function A000010.at n=46A333291
• Number of compositions of n where each part after the first is either twice or half the prior part.at n=58A342331
• Number of integer partitions of n of length > 2 whose second differences have median 0.at n=38A360682