22972

Appears in sequences

• Numbers k such that 10*R_k + 7 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=15A056655
• Expansion of x * phi(x) * psi(x^14) / (f(-x) * f(-x^7)) in powers of x where phi(), psi(), f() are Ramanujan theta functions.at n=30A193883
• Half the number of 0..4 arrays of length n+2 with second differences nonzero.at n=4A212778
• T(n,k)=Half the number of 0..k arrays of length n+2 with second differences nonzero.at n=32A212782
• Half the number of 0..n arrays of length 7 with second differences nonzero.at n=3A212786
• Numbers k such that decimal expansion of k^2 can be split into two parts whose sum is a number with repeated digits.at n=50A328173
• Numerator of (1+sigma(s)) / ((s+1)/2), where s is the square of n prime-shifted once (s = A003961(n)^2 = A003961(n^2)).at n=29A337338
• Expansion of g/(2 - g^2)^2, where g = 1+x*g^4 is the g.f. of A002293.at n=5A391466