A374101 Numbers k such that k and k+2 are both self numbers (A003052).

1, 3, 5, 7, 108, 209, 310, 411, 512, 613, 714, 815, 916, 1109, 1210, 1311, 1412, 1513, 1614, 1715, 1816, 1917, 2110, 2211, 2312, 2413, 2514, 2615, 2716, 2817, 2918, 3111, 3212, 3313, 3414, 3515, 3616, 3717, 3818, 3919, 4112, 4213, 4314, 4415, 4516, 4617, 4718

Offset: 1

Author

Amiram Eldar, Jun 28 2024

Keywords

• nonn
• base
• easy

Comments

The least difference between consecutive self numbers is 2 (see Griffin N. Macris's proof at A010061 that may be adapted to other bases).

Links

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

Crossrefs

Subsequence of A003052.

Cf. A010061, A339216 (binary analog).

Programs

Mathematica

seq[max_] := Module[{c = Complement[Range[max], Table[n + DigitSum[n], {n, 1, max}]], d, ind}, d = Differences[c]; ind = Position[d, 2] // Flatten; c[[ind]]]; seq[5000]