A048783 Numbers k such that prime(k) - sigma(k) - phi(k) = prime(k+1) - sigma(k+1) - phi(k+1), where sigma(k) = sum of divisors of k.

2, 33, 57, 62, 142, 201, 253, 302, 501, 542, 745, 877, 878, 913, 921, 1153, 1198, 1201, 1477, 1642, 1942, 1982, 2041, 2326, 2362, 2605, 2973, 3046, 3226, 3273, 3326, 3493, 3517, 3601, 3646, 3694, 3733, 3826, 3865, 3902, 4054, 4261, 4273, 4357, 4414, 4573

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Prog

(PARI) isok(n) = (prime(n) - sigma(n) - eulerphi(n) == prime(n+1) - sigma(n+1) - eulerphi(n+1)) \\ Michel Marcus, Jul 14 2013
(PARI) list(lim) = {my(v1 = -1, k = 0, f); forprime(p = 1, lim, k++; f = factor(k); v2 = p - sigma(f) - eulerphi(f); if(v2 == v1, print1(k-1, ", ")); v1 = v2); } \\ Amiram Eldar, Mar 06 2026

Crossrefs

Cf. A000040, A000203, A000010.

Sequence in context: A316736 A199551 A045932 * A116340 A003347 A303375

Adjacent sequences: A048780 A048781 A048782 * A048784 A048785 A048786

Keyword

easy,nonn

Author

Naohiro Nomoto

Status

approved