A284646 Variation on Leyland numbers: k = x'^y + y'^x, where x' and y' are the arithmetic derivative of x and y.

2, 17, 26, 37, 50, 65, 82, 101, 126, 145, 170, 197, 217, 226, 257, 325, 344, 362, 401, 442, 485, 512, 513, 577, 626, 677, 730, 785, 901, 962, 1001, 1025, 1090, 1157, 1297, 1445, 1522, 1601, 1682, 1729, 1765, 1850, 1937, 2026, 2117, 2198, 2305, 2402, 2501, 2602

Offset

1,1

Comments

Another similar variation on Leyland numbers is k = x^y' + y^x' that leads to A014091.

Links

Table of n, a(n) for n=1..50.

Example

2' = 1, 4' = 4, 1^4 + 4^2 = 1 + 16 = 17.

Maple

with(numtheory): N:= 10^5: A:={}: for x from 2 to floor(N^(1/2)) do
for y from 2 do yd:=y*add(op(2, p)/op(1, p), p=ifactors(y)[2]); xd:=x*add(op(2, p)/op(1, p), p=ifactors(x)[2]); a:= xd^y + yd^x;
if a>N then break fi; A:=A union {a}; od; od; sort([op(A)]);
# based on Robert Israel code in A076980.

Crossrefs

Cf. A014091, A076980.

Sequence in context: A086322 A340048 A164275 * A270344 A300134 A171605

Adjacent sequences: A284643 A284644 A284645 * A284647 A284648 A284649

Keyword

nonn

Author

Paolo P. Lava, Mar 31 2017

Status

approved