A277848 - OEIS

A277848

Index at which n occurs in A217727, or 0 if there is no such index.

1, 7, 2, 5, 18, 21, 11, 8, 28, 35, 46, 74, 54, 25, 3, 129, 32, 39, 78, 58, 133, 43, 62, 6, 95, 91, 152, 171, 87, 71, 190, 16, 148, 328, 19, 181, 167, 51, 227, 405, 618, 355, 344, 254, 440, 83, 926, 22, 67, 277, 100, 157, 1400, 195, 333, 186, 1144, 232, 259, 445, 282, 105, 12, 237, 110, 115, 388, 211, 468, 383, 492, 144, 594, 307, 366, 206, 126, 533, 324, 9, 463, 642

(list; graph; refs; listen; history; text; internal format)

OFFSET

2,2

COMMENTS

It is conjectured that all integers >= 2 appear in A217727.

LINKS

Table of n, a(n) for n=2..83.

PROG

(PARI) A277848(n, a=2, u=[])={for(i=1, 9e9, a==n&&return(i); u=setunion(u, [a]); while(#u>1&&u[2]==u[1]+1, u=u[^1]); my(t=log(a)\1); a=if(t>u[1]&&!setsearch(u, t), t, a^2))} \\ This code computes ("for each n") the sequence A217727 up to the index where n occurs.

(PARI) A277848_vec(N, a=2, u=[], v=vector(N))={my(i=1, t); until(u[1]>N, a<=N&&v[a]=i; u=setunion(u, [a]); while(#u>1&&u[2]==u[1]+1, u=u[^1]); i++; a=if((t=log(a)\1)>u[1]&&!setsearch(u, t), t, a^2)); v[^1]} \\ This is more efficient to compute a whole range a(1..N).

CROSSREFS

Cf. A217727, A114183.

Sequence in context: A280234 A368383 A073652 * A248285 A117029 A128475

Adjacent sequences: A277845 A277846 A277847 * A277849 A277850 A277851

KEYWORD

nonn

AUTHOR

M. F. Hasler, Nov 20 2016

STATUS

approved