A353265 Partial sums of A208981.

0, 0, 3, 3, 4, 8, 20, 20, 35, 37, 47, 52, 57, 70, 83, 83, 91, 107, 123, 126, 127, 138, 149, 155, 174, 180, 287, 301, 315, 329, 431, 431, 453, 462, 471, 488, 505, 522, 552, 556, 661, 663, 688, 700, 712, 724, 824, 831, 851, 871, 891, 898, 905, 1013, 1121, 1136, 1164, 1179, 1207, 1222, 1237, 1340, 1443, 1443

Offset

1,3

Links

Paolo Xausa, Table of n, a(n) for n = 1..10000

Index entries for sequences related to 3x+1 (or Collatz) problem

Mathematica

Accumulate @ Table[-1 + Length @ NestWhileList[If[OddQ[#], 3*# + 1, #/2] &, n, ! IntegerQ @ Log[2, #] &], {n, 1, 64}] (* Amiram Eldar, Apr 09 2022 *)

Prog

(PARI) ispow2(n)=n>>=valuation(n, 2); n==1;
f(n) = my(s); while(!ispow2(n), n=if(n%2, 3*n+1, n/2); s++); s; \\ A208981
a(n) = sum(i=1, n, f(i)); \\ Michel Marcus, Apr 13 2022

Crossrefs

Cf. A208981, A347270 (gives all 3x+1 sequences).

Cf. A006370, A006877, A014682, A347272, A347519, A352907, A352908, A352939.

Sequence in context: A019466 A111573 A049854 * A366758 A291872 A195978

Adjacent sequences: A353262 A353263 A353264 * A353266 A353267 A353268

Keyword

nonn

Author

Omar E. Pol, Apr 09 2022

Status

approved