A287884 a(n) = A287883(2^n).

1, 3, 28, 285, 2874, 29207, 293858, 2947737, 29514646, 295386007, 2955097334, 29553146265, 295558787590, 2955735778303, 29557796658178, 295579887348019, 2955811931652374, 29558179966812569, 295582026870344468, 2955821271264504051, 29558218775337316364, 295582213433030953645

Offset

0,2

Comments

These are the terms where A287883 makes a dramatic jump.

It would be nice to have a formula.

Links

Jinyuan Wang, Table of n, a(n) for n = 0..30

Mathematica

co[n_, k_]:=Nest[Flatten[IntegerDigits[{#, n}]]&, n, k-1]; A037276=Table[FromDigits[Flatten[IntegerDigits[co@@@FactorInteger[n]]]], {n, 3 10^5}]; Table[Sum[A037276[[k]], {k, 1, 2^n}], {n, 0, 18}] (* Vincenzo Librandi, Oct 01 2017 *)

Prog

(PARI) A037276(k) = {for(i=1, #k=factor(k)~, k[1, i]=concat(vector(k[2, i], j, Str(k[1, i])))); eval(concat(k[1, ])); }
lista(nn) = {my(s=1); print1(s); for(n=0, nn, s+=sum(k=2^n+1, 2*2^n, A037276(k)); print1(", ", s)); } \\ Jinyuan Wang, Feb 19 2020

Crossrefs

Cf. A037276, A287883.

Sequence in context: A026114 A181069 A239297 * A250890 A199754 A277507

Adjacent sequences: A287881 A287882 A287883 * A287885 A287886 A287887

Keyword

nonn,base

Author

N. J. A. Sloane, Jun 20 2017

Extensions

a(15)-a(18) from Vincenzo Librandi, Oct 01 2017

a(19)-a(21) from Jinyuan Wang, Feb 19 2020

Status

approved