Sequences

Numbers k such that sigma(k) = sigma(k+3).

Inverse of 1853rd cyclotomic polynomial.

Numbers k such that sigma(k) = sigma(k+4).

Inverse of 1855th cyclotomic polynomial.

Numbers k such that sigma(k) = sigma(k+5).

Numbers k such that sigma(k) = sigma(k+6).

Numbers k such that sigma(k) = sigma(k+7).

Inverse of 1859th cyclotomic polynomial.

Inverse of 1860th cyclotomic polynomial.

Numbers k such that phi(k + 4) | sigma(k) + 4.

Numbers k such that phi(k + 5) | sigma(k) + 5.

Numbers k such that phi(k + 6) | sigma(k) + 6.

Numbers k such that phi(k + 8) | sigma(k) + 8.

Numbers k such that phi(k + 10) | (sigma(k) + 10).

Numbers k such that phi(k + 12) | sigma(k) + 12.

Numbers k such that sigma(k) = sigma(k+8).

Numbers k such that sigma(k) = sigma(k+9).

Inverse of 1869th cyclotomic polynomial.

Inverse of 1870th cyclotomic polynomial.

Numbers k such that sigma(k) = sigma(k+10).

Numbers k such that sigma(k) = sigma(k+11).

Numbers k such that sigma(k) = sigma(k+12).

Numbers k such that sigma(k) = sigma(k+13).

A modified Pierce-type expansion for Pi: Pi = a(0) + Sum_{n>=1} (-1)^floor(n/2)/(Product_{i=1..n} a(i)).

Inverse of 1876th cyclotomic polynomial.

a(n) = smallest number k such that sigma(k + n) = sigma(k) + n, or -1 if no such number exists.

Erroneous version of A007015.

Numbers k such that k | (3^k + 3).

Numbers k that divide 4^k + 4.

Inverse of 1881st cyclotomic polynomial.

Numbers k such that k | 5^k + 5.

Numbers k such that k | 6^k + 6.

Numbers k such that k | 7^k + 7.

Inverse of 1885th cyclotomic polynomial.

Inverse of 1886th cyclotomic polynomial.

Inverse of 1887th cyclotomic polynomial.

Numbers k such that k | 8^k + 8.

Numbers k such that k | 9^k + 9.

Inverse of 1890th cyclotomic polynomial.

Inverse of 1891st cyclotomic polynomial.

Inverse of 1892nd cyclotomic polynomial.

Numbers k such that k | 10^k + 10.

Numbers n such that n | 11^n + 11.

Numbers k such that k | 12^k + 12.

Numbers k such that k | 13^k + 13.

First k>n such that k | n^k + n.

Inverse of 1898th cyclotomic polynomial.

Smallest odd k>n such that k | n^k + n, or 0 if n=2^m.

a(n) = smallest k >= 1 such that n divides k^n + k.

a(n) = 2^n mod n.