A338510 a(n) is smallest number in column n >= 0 of the triangle in A247687.

9, 50, 484, 2312, 21904, 143648, 1098304, 8454272, 69488896, 544236032, 4315964416, 34410088448, 276019941376, 2206276984832, 17595407417344, 140741783355392, 1126398178164736, 9007405414350848, 72063366589579264, 576468448910508032, 4611760785521115136

Offset

0,1

Comments

Since sigma(a(n)) = (2^(n+1) - 1)*(1 + p_n + (p_n)^2) where p_n = A014210(n+1), lim_{n->infinity} sigma(a(n)) = 2*a(n).

Links

Table of n, a(n) for n=0..20.

Formula

a(n) = 2^n * A014210(n+1)^2, n >= 0.

Example

a(4) = 16 * 37^2 = 21904 since 37 is the first prime larger than 32.

Mathematica

a338510[n_] := 2^n NextPrime[2^(n+1)]^2/; n>=0
Map[a338510, Range[0, 20]]

Crossrefs

Cf. A014210, A237593, A247687.

Sequence in context: A115366 A188210 A308646 * A221246 A002462 A210061

Adjacent sequences: A338507 A338508 A338509 * A338511 A338512 A338513

Keyword

nonn

Author

Hartmut F. W. Hoft, Oct 31 2020

Status

approved