40131

Appears in sequences

• Odd numbers k that divide phi(k)*sigma(k).at n=23A015706
• Numbers k whose decimal representation, read as a base-19 value and divided by k, yields an integer.at n=18A032569
• a(1)=10; if n = Product p_i^e_i, n > 1, then a(n) = Product p_{i+1}^e_i * Product p_{i+3}^e_i.at n=19A045973
• Nonpalindromic numbers k such that k is not divisible by 10 and k*R(k) is a square, where R(k) is the reversal of k (A004086).at n=31A062917
• Numbers k such that all the following properties hold: (i) k*reverse(k) is a square; (ii) k != reverse(k); (iii) k and reverse(k) are not both squares; and (iv) k and reverse(k) have the same number of digits.at n=20A082994
• Fifth column (m=4) of (1,6)-Pascal triangle A096956.at n=25A096958
• Numbers k such that 10^k + 5*R_k + 4 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=26A102938
• Least multiple of 2n-1 ending in prime(n), 0 if no such number exists.at n=31A114780
• Pairs of deficient numbers having the same value of sigma(k)/k in the order that they are found.at n=25A211680
• The larger companion to the deficient numbers in A212608.at n=12A212609
• Pairs of primitive deficient numbers having the same value of sigma(k)/k, listed by increasing value of the larger of the two k values.at n=5A212610
• The larger companion to the primitive deficient numbers in A212611.at n=2A212612
• Larger member of primitive friendly pairs ordered by smallest maximal element.at n=29A233039
• Numbers k such that squarefree part of sigma(k) is equal to squarefree part of 2*k.at n=14A331752
• Numbers k such that A071324(k) = A071324(k+1).at n=20A333261
• Factorial base Niven numbers (A118363) with a record gap to the next factorial base Niven number.at n=19A347495
• Numbers k such that A005940(k) is either k itself or its descendant in Doudna-tree, A005940.at n=46A364960
• Odd numbers k such that A005940(k) is either k itself or its descendant in Doudna-tree, A005940.at n=6A364961
• Numbers k such that k + 1 divides 3^k + 1.at n=10A370578
• Expansion of g*(1 + x*g^3), where g = 1+x*g^5 is the g.f. of A002294.at n=6A391382