A065900 Numbers n such that sigma(n) = sigma(n-1) + sigma(n-2).

3, 4, 24, 1968, 3264, 5016, 60456, 1016508, 4420164, 12055512, 14365608, 25726728, 27896424, 66562308, 72764736, 98734968, 175186656, 224868312, 253694928, 288657204, 386668344, 421575408, 504737748, 630645456, 1493548000, 1653797796, 2120325012, 2221315152

Offset: 1

Author

Jason Earls, Dec 07 2001

Keywords

• nonn

Comments

No other terms less than 1000000000. - Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 23 2004

Links

• Donovan Johnson and Giovanni Resta, Table of n, a(n) for n = 1..112 (terms < 10^13, first 50 terms from Donovan Johnson)

Crossrefs

Cf. A000203, A076530, A104149.

Programs

PARI

s1=1; s2=3; for(n=3, 10^8, s3=sigma(n); if(s3==s1+s2, print1(n ", ")); s1=s2; s2=s3) /* Donovan Johnson, Apr 06 2013 */

Formula

a(n) = A076530(n) + 1 = A104149(n) + 2. - Alex Ratushnyak, Jul 06 2013

Extensions

More terms from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 23 2004