30256

Appears in sequences

• Octagonal pyramidal numbers: a(n) = n*(n+1)*(2*n-1)/2.at n=30A002414
• Numbers k such that phi(k) and sigma(k) are both perfect squares.at n=17A067781
• a(n) = (n+1)*(2*n+1)*(4*n+1).at n=15A079588
• Numbers k such that sigma(k) divides k^2.at n=25A090777
• Given the infinite continued fraction (1+i)+((1+i)/(1+i)+((1+i)/((1+i)+...)))), where i is the square root of (-1), this is the numerator of the imaginary part of the convergents.at n=14A093726
• Structured icosidodecahedral numbers.at n=15A100147
• Admirable numbers n such that the subtracted divisor is > sqrt(n).at n=38A109321
• a(n) = coefficient of x^n in the (2^(n+1))-th iteration of x+x^2 for n>=1.at n=3A158263
• Table where row n lists the coefficients in the (2^n)-th iteration of x+x^2 for n>=0, read by antidiagonals not including trailing zeros in rows.at n=30A158264
• Number of reduced words of length n in Coxeter group on 32 generators S_i with relations (S_i)^2 = (S_i S_j)^3 = I.at n=3A162836
• Numbers d*p where d is a perfect number and p<d a prime not dividing d.at n=24A165772
• a(n) = 2*(Lucas(n)^2 - (-1)^n).at n=10A171089
• Number of binary arrays of length n+9 with fewer than 5 ones in any length 10 subsequence (=less than 50% duty cycle).at n=8A213115
• Even octagonal pyramidal numbers (A002414).at n=14A218327
• Consider a number n with m decimal digits, m>9. The sequence lists the numbers n such that the prefix of length m-1 and the suffix of length m-1 are both perfect squares.at n=35A244283
• Numbers whose sum of divisors is the square of one of their divisors.at n=5A303123
• Numbers k for which A003415(k) >= A276086(k) > k, where A003415 is the arithmetic derivative and A276086 is the primorial base exp-function.at n=14A351229
• Numbers k such that (A276086(k)/s)^s >= k^(s-1) and A276086(k) <= A003415(k), where A003415 is the arithmetic derivative, A276086 is the primorial base exp-function, and s = bigomega(k).at n=41A370128
• Numbers k such that A322582(k) <= A276086(k) <= A348507(k).at n=45A392602