A392496 - OEIS

%I #12 Mar 03 2026 03:59:34

%S 20,70,88,104,272,304,350,368,464,572,650,836,1184,1312,1376,1504,

%T 1696,1888,1952,3770,4030,4288,4544,4672,5056,5312,5696,5704,5810,

%U 5830,6208,6464,6592,6790,6808,6848,6976,7144,7192,7232,7630,7910,7912,8024,8056,9272,9590,9730

%N 2-rigid numbers. p-rigid numbers where p is prime are defined in A392499.

%C Also the numbers that are sum-irreducible and abundant.

%H Peter Luschny, <a href="https://github.com/PeterLuschny/Gists/blob/main/ComposableRigidSparse.ipynb">Composable, rigid, and sparse numbers</a>. A Python notebook.

%o (Python) # Function 'is_rigid' is defined in A392499 (see also links).

%o def A392496_list(upto: int) -> list[int]:

%o     return [n for n in range(20, upto+1, 2) if 2 == is_rigid(n)]

%o print(A392496_list(9731))

%Y Cf. A005101 (abundant), A392650 (sum-irreducible), A006036, A392495 (p=3), A392499.

%K nonn

%O 1,1

%A _Peter Luschny_, Jan 16 2026