A063693 Numbers k such that phi(k + d(k)) = phi(k) + d(k), where phi() = A000010(), d() = A000005().

3, 5, 11, 17, 24, 29, 41, 42, 56, 59, 71, 98, 101, 102, 107, 137, 149, 179, 191, 197, 227, 230, 239, 248, 264, 269, 281, 294, 311, 347, 419, 431, 461, 468, 521, 569, 599, 617, 638, 641, 659, 809, 821, 827, 857, 881, 1014, 1016, 1019, 1031, 1049, 1061, 1078

Offset

1,1

Links

Harry J. Smith, Table of n, a(n) for n = 1..1000

Example

Primes and composites among solutions:
k = 59, d(58) = 2, phi(59) = 58, phi(59+2) = phi(61) = 60 = phi(59) + d(59);
k = 56, d(56) = 8, phi(56) = 24, phi(56+8) = phi(64) = 32 = phi(56) + d(56).

Prog

(PARI) { n=0; for (x=1, 10^9, if (eulerphi(x + numdiv(x)) == (eulerphi(x) + numdiv(x)), write("b063693.txt", n++, " ", x); if (n==1000, break)) ) } \\ Harry J. Smith, Aug 27 2009

Crossrefs

Cf. A000005, A000010.

Sequence in context: A158318 A099596 A200748 * A258713 A267517 A309427

Adjacent sequences: A063690 A063691 A063692 * A063694 A063695 A063696

Keyword

nonn

Author

Labos Elemer, Aug 23 2001

Status

approved