A337275 Index of appearance of 2*prime(n) in A336957, or -1 if 2*prime(n) never appears.

-1, 3, 10, 6, 14, 18, 22, 23, 26, 51, 46, 54, 58, 87, 99, 106, 107, 110, 114, 134, 135, 142, 155, 171, 182, 195, 199, 215, 210, 214, 255, 259, 271, 274, 295, 299, 315, 323, 326, 347, 367, 371, 390, 391, 394, 398, 443, 451, 471, 475, 478, 491, 495, 511, 523, 531, 543, 547, 567, 575, 579, 599, 627

Offset: 1

Author

N. J. A. Sloane, Sep 09 2020

Keywords

• sign

Comments

It is a strong conjecture that 2*prime(n) appears in A336957 for all n>1, and it is known that 4 does not appear.

See also the comment in A336957 discussing when primes first appear in A336957.

Examples

			A336957(14) = 22 = 2*prime(5), so a(5) = 14.
		

Links

• N. J. A. Sloane, Table of n, a(n) for n = 1..20000
• N. J. A. Sloane, Table comparing the present sequence and A338074

Crossrefs

Cf. A336957, A337276, A338074.