A002381 Numbers of the form (p^2 - 1)/120 where p is 1 or prime. (Formerly M2614 N1034)

0, 1, 3, 7, 8, 14, 29, 31, 42, 52, 66, 85, 99, 143, 161, 185, 190, 267, 273, 304, 330, 371, 437, 476, 484, 525, 603, 612, 658, 806, 913, 1015, 1074, 1197, 1261, 1340, 1394, 1463, 1477, 1548, 1606, 1680, 1771, 1912, 2009, 2075, 2159, 2262, 2439, 2698, 2717

Offset

1,3

Comments

For n>1, primes p corresponding to a(n) are in A038872(n) = A045468(n-1) = A141158(n). - Ray Chandler, Jul 29 2019

References

H. Gupta, On a conjecture of Chowla, Proc. Indian Acad. Sci., 5A (1937), 381-384.

N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Ray Chandler, Table of n, a(n) for n = 1..10000

H. Gupta, On a conjecture of Chowla, Proc. Indian Acad. Sci., 5A (1937), 381-384. [Annotated scanned copy]

Mathematica

Join[{0}, Select[Table[(p^2-1)/120, {p, Prime[Range[200]]}], IntegerQ]] (* Harvey P. Dale, Jan 14 2020 *)

Prog

(PARI) j=[]; for(n=0, 150, x=prime(n)^2-1; if(Mod(x, 120)==0, j=concat(j, (x/120)))); j

Crossrefs

Cf. A002382, A002855, A038872, A045468, A141158, subsequence of A093722.

Sequence in context: A067064 A093722 A309745 * A131559 A366783 A051211

Adjacent sequences: A002378 A002379 A002380 * A002382 A002383 A002384

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Jason Earls, Jul 29 2001

Status

approved