A382148 Index of first occurrence of n in A381238, or -1 if n does not appear there.

0, 14, 1, 3, 79, 11, 30, 8, 108, 17, 6, 111, 169, 18, 76, 78, 74, 388, 239, 86, 383, 345, 191, 1017, 178, 486, 163, 1828, 209, 364, 484, 582, 160, 289, 436, 878, 174, 320, 37, 1029, 698, 1386, 768, 618, 558, 212, 1318, 2213, 826, 350, 877, 1780, 1033, 407, 188, 229, 1478, 467, 305

Offset

1,2

Links

Table of n, a(n) for n=1..59.

Mathematica

b[n_] := b[n] = Sec[b[n-1]]^2; b[0] = 1; With[{v = Floor[Array[b, 600, 0]]}, -1 + TakeWhile[FirstPosition[v, #] & /@ Range[Max[v]], ! MissingQ[#] &] // Flatten] (* Amiram Eldar, Mar 18 2025 *)

Crossrefs

Cf. A381238.

Sequence in context: A160495 A040204 A040203 * A040205 A171693 A235704

Adjacent sequences: A382145 A382146 A382147 * A382149 A382150 A382151

Keyword

nonn

Author

N. J. A. Sloane, Mar 17 2025

Extensions

More terms from Amiram Eldar, Mar 18 2025

Status

approved